Past SARS-CoV-2 infection protection against re-infection: a systematic review and meta-analysis

Planning and adjusting the COVID-19 booster vaccination campaign to reduce disease burden

As public health policies shifted in 2023 from emergency response to long-term COVID-19 disease management, immunization programs started to face the challenge of formulating routine booster campaigns in a still highly uncertain seasonal behavior of the COVID-19 epidemic. Mathematical models assessing past booster campaigns and integrating knowledge on waning of immunity can help better inform current and future vaccination programs. Focusing on the first booster campaign in the 2021/2022 winter in France, we used a multi-strain age-stratified transmission model to assess the effectiveness of the observed booster vaccination in controlling the succession of Delta, Omicron BA.1 and BA.2 waves. We explored counterfactual scenarios altering the eligibility criteria and inter-dose delay. Our study showed that the success of the immunization program in curtailing the Omicron BA.1 and BA.2 waves was largely dependent on the inclusion of adults among the eligible groups, and was highly sensitive to the inter-dose delay, which was changed over time. Shortening or prolonging this delay, even by only one month, would have required substantial social distancing interventions to curtail the hospitalization peak. Also, the time window for adjusting the delay was very short. Our findings highlight the importance of readiness and adaptation in the formulation of routine booster campaign in the current level of epidemiological uncertainty.

COVID-19 vaccination perspectives among patients with Long COVID: A qualitative study

Individuals who have Long COVID may have unique perspectives about COVID-19 vaccination due to the significant impact that COVID-19 has had on their lives. However, little is known about the specific vaccination perspectives among this patient population. The goal of our study was to improve our understanding of perspectives about COVID-19 vaccines among individuals with Long COVID. Interviews were conducted with patients receiving care at a post-COVID recovery clinic. Deductive thematic analysis was used to characterize participant perspectives according to the vaccine acceptance continuum framework, which recognizes a spectrum from vaccine acceptance to refusal. From interviews with 21 patients, we identified perspectives across the continuum of vaccine acceptance. These perspectives included acceptance of vaccines to prevent future illness, concerns about vaccine side effects on Long COVID symptoms, and refusal of vaccines due to perceived natural immunity. A limitation of our study is that these perspectives are specific to individuals receiving care at one post-COVID recovery clinic. In conclusion, our study demonstrates that some patients with Long COVID are uncertain about COVID-19 vaccines and boosters but may also be amenable to conversations that impact future vaccination acceptance. Patient perspectives should be considered when communicating recommendations for COVID-19 vaccinations to this population.

Effectiveness and durability of mRNA-1273 BA.4/BA.5 bivalent vaccine (mRNA-1273.222) against SARS-CoV-2 BA.4/BA.5 and XBB sublineages

Emerging SARS-CoV-2 sublineages continue to cause serious COVID-19 disease, but most individuals have not received any COVID-19 vaccine for >1 year. Assessment of long-term effectiveness of bivalent COVID-19 vaccines against circulating sublineages is important to inform the potential need for vaccination with updated vaccines. In this test-negative study at Kaiser Permanente Southern California, sequencing-confirmed BA.4/BA.5- or XBB-related SARS-CoV-2-positive cases (September 1, 2022 to June 30, 2023), were matched 1:3 to SARS-CoV-2-negative controls. We assessed mRNA-1273 bivalent relative (rVE) and absolute vaccine effectiveness (VE) compared to ≥2 or 0 doses of original monovalent vaccine, respectively. The rVE analysis included 20,966 cases and 62,898 controls. rVE (95%CI) against BA.4/BA.5 at 14-60 days and 121-180 days was 52.7% (46.9-57.8%) and 35.5% (-2.8-59.5%) for infection, and 59.3% (49.7-67.0%) and 33.2% (-28.2-68.0%) for Emergency Department/Urgent Care (ED/UC) encounters. For BA.4/BA.5-related hospitalizations, rVE was 71.3% (44.9-85.1%) and 52.0% (-1.2-77.3%) at 14-60 days and 61-120 days, respectively. rVE against XBB at 14-60 days and 121-180 days was 48.8% (33.4-60.7%) and -3.9% (-18.1-11.3%) for infection, 70.7% (52.4-82.0%) and 15.7% (-6.0-33.2%) for ED/UC encounters, and 87.9% (43.8-97.4%) and 57.1% (17.0-77.8%) for hospitalization. VE and subgroup analyses (age, immunocompromised status, previous SARS-CoV-2 infection) results were similar to rVE analyses. rVE of mRNA-1273 bivalent vaccine against BA.4/BA.5 and XBB infections, ED/UC encounters, and hospitalizations waned over time. Periodic revaccination with vaccines targeting emerging variants may be important in reducing COVID-19 morbidity and mortality.

Dynamics of SARS-CoV-2 antibodies after natural infection: insights from a study on Pasteur Institute of Tunis employees

This study aimed to assess the kinetics of antibodies against the SARS-CoV-2, following natural infection in a cohort of employees of the Institut Pasteur de Tunis (IPT) and to assess the risk of reinfection over a 12-months follow-up period. A prospective study was conducted among an open cohort of IPT employees with confirmed SARS-CoV-2 infection that were recruited between September 2020 and March 2021. Sera samples were taken at 1, 3, 6, 9 and 12 months after confirmation of COVID-19 infection and tested for SARS-CoV-2-specific immunoglobulin G (IgG) antibodies to the spike (S-RBD) protein (IgG anti-S-RBD) and for neutralizing antibodies. Participants who had an initial decline of IgG anti-S-RBD and neutralizing antibodies followed by a subsequent rise in antibody titers as well as those who tested positive for SARS-CoV-2 by RT-PCR after at least 60 days of follow up were considered as reinfected. In total, 137 individuals were included with a mean age of 44.7 ± 12.3 years and a sex-ratio (Male/Female) of 0.33. Nearly all participants (92.7%) were symptomatic, and 2.2% required hospitalization. Among the 70 participants with three or more prospective blood samples, 32.8% were reinfected among whom 11 (47.8%) reported COVID-19 like symptoms. Up to 12 months of follow up, 100% and 42.9% of participants had detectable IgG anti-S-RBD and neutralizing antibodies, respectively. This study showed that humoral immune response following COVID-19 infection may persist up to 12 months after infection despite the potential risk for reinfection that is mainly explained by the emergence of new variants.

Fc-empowered exosomes with superior epithelial layer transmission and lung distribution ability for pulmonary vaccination

Mucosal vaccines offer potential benefits over parenteral vaccines for they can trigger both systemic immune protection and immune responses at the predominant sites of pathogen infection. However, the defense function of mucosal barrier remains a challenge for vaccines to overcome. Here, we show that surface modification of exosomes with the fragment crystallizable (Fc) part from IgG can deliver the receptor-binding domain (RBD) of SARS-CoV-2 to cross mucosal epithelial layer and permeate into peripheral lung through neonatal Fc receptor (FcRn) mediated transcytosis. The exosomes F-L-R-Exo are generated by genetically engineered dendritic cells, in which a fusion protein Fc-Lamp2b-RBD is expressed and anchored on the membrane. After intratracheally administration, F-L-R-Exo is able to induce a high level of RBD-specific IgG and IgA antibodies in the animals' lungs. Furthermore, potent Th1 immune-biased T cell responses were also observed in both systemic and mucosal immune responses. F-L-R-Exo can protect the mice from SARS-CoV-2 pseudovirus infection after a challenge. These findings hold great promise for the development of a novel respiratory mucosal vaccine approach.

Risk of reinfection and severity with the predominant BA.5 Omicron subvariant China, from December 2022 to January 2023

Data on reinfection in large Asian populations are limited. In this study, we aimed to evaluate the reinfection rate, disease severity, and time interval between the infections in the symptomatic and asymptomatic populations which are firstl infected with BA.2 Omicron Variant. We retrospectively included adult patients with COVID-19 discharged from four designated hospitals between 27 April 2021 and 30 November 2022, who were interviewed via telephone from 29 January to 1 March 2023. Univariable and multivariable analyses were used to explore risk factors associated with reinfection. A total of 16,558 patients were followed up, during the telephone survey of an average of 310.0 days, 1610 (9.72%) participants self-reported reinfection. The mean time range of reinfection was 257.9 days. The risks for reinfection were analysed using multivariable logistic regression. Patients with severe first infection were at higher risk for reinfection (aORs, 2.50; P < 0.001). The male (aORs,0.82; P < 0.001), the elderly (aORs, 0.44; P < 0.001), and patients with full vaccination (aORs, 0.67; P < 0.001) or booster (aORs, 0.63; P < 0.001) had the lower risk of reinfection. Patients over 60 years of age (aORs,9.02; P = 0.006) and those with ≥2 comorbidities (aORs,11.51; P = 0.016). were at higher risk for severe reinfection. The number of clinical manifestations of reinfection increases in people with severe first infection (aORs, 2.82; P = 0.023). The overall reinfection rate was 9.72%, and the reinfection rate of Omicron-to-Omicron subvariants was 9.50% at one year. The severity of Omicron-Omicron reinfection decreased. Data from our clinical study may provide clinical evidence and bolster response preparedness for future COVID-19 reinfection waves.

A prediction of mutations in infectious viruses using artificial intelligence

Many subtypes of SARS-CoV-2 have emerged since its early stages, with mutations showing regional and racial differences. These mutations significantly affected the infectivity and severity of the virus. This study aimed to predict the mutations that occur during the evolution of SARS-CoV-2 and identify the key characteristics for making these predictions. We collected and organized data on the lineage, date, clade, and mutations of SARS-CoV-2 from publicly available databases and processed them to predict the mutations. In addition, we utilized various artificial intelligence models to predict newly emerging mutations and created various training sets based on clade information. Using only mutation information resulted in low performance of the learning models, whereas incorporating clade differentiation resulted in high performance in machine learning models, including XGBoost (accuracy: 0.999). However, mutations fixed in the receptor-binding motif (RBM) region of Omicron resulted in decreased predictive performance. Using these models, we predicted potential mutation positions for 24C, following the recently emerged 24A and 24B clades. We identified a mutation at position Q493 in the RBM region. Our study developed effective artificial intelligence models and characteristics for predicting new mutations in continuously evolving infectious viruses.

School Mask Mandates and COVID-19: The Challenge of Using Difference-in-Differences Analysis of Observational Data to Estimate the Effectiveness of a Public Health Intervention

BACKGROUND

There are considerable challenges when using difference-in-differences (DiD) analysis of ecological data to estimate the effectiveness of public health interventions in rapidly changing situations.

OBJECTIVE

To discuss the shortcomings of DiD methodology for the estimation of the effects of public health interventions using ecological data.

DESIGN

As an example, the authors consider an analysis that used DiD methodology and reported a causal reduction in COVID-19 cases due to the maintenance of school mask mandates. They did alternate analyses using various control groups to assess the robustness of the prior analysis.

SETTING

School districts in the greater Boston area and Massachusetts during the 2021-to-2022 academic year.

PARTICIPANTS

Students and school staff.

MEASUREMENTS

Changes in COVID-19 case rates in districts that did and did not lift mask mandates.

RESULTS

Important potential confounders rendered DiD methodology inappropriate for causal inference, including prior immunity, temporal variation in rates of infection, and changes in testing practices. The racial composition and income of intervention and control groups also differed substantially. Compared with maintaining the mask requirement, dropping the requirement was associated with anywhere from an increase of 5.64 cases (95% CI, 3.00 to 8.29 cases) per 1000 persons to a decrease of 2.74 cases (CI, 0.63 to 4.85 cases) per 1000 persons, depending on choice of control group and whether students or staff were examined.

LIMITATION

Ecological data were used; detailed data on all potential confounders were unavailable.

CONCLUSION

Alternate analyses yielded estimates consistent with a wide range of both negative and positive associations in COVID-19 case rates after removal of mask mandates. The findings highlight the challenges of using DiD analysis of ecological data to estimate the effectiveness of interventions in divergent intervention and control groups during rapidly changing circumstances.

PRIMARY FUNDING SOURCE

None.

Effectiveness of the First and Second Severe Acute Respiratory Syndrome Coronavirus 2 Vaccine Dose: A Nationwide Cohort Study From Austria on Hybrid Versus Natural Immunity

Background

We aimed to evaluate the effectiveness of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccinations in previously SARS-CoV-2-infected adults in the general population of Austria during the Delta wave and with extended follow-up.

Methods

In a nationwide retrospective cohort study, we calculated age-, sex-, and nursing home residency-adjusted Cox proportional hazard ratios (HRs) of coronavirus disease 2019 (COVID-19) deaths, SARS-CoV-2 infections, and non-COVID-19 deaths from 1 October to 31 December 2021, and secondarily with extended follow-up to 30 June 2022. Relative vaccine effectiveness (rVE) is rVE = (1 - HR) × 100.

Results

Among 494 646 previously infected adults, 169 543 had received 2 vaccine doses, 133 567 had received 1 dose, and 190 275 were unvaccinated at baseline. We recorded 17 COVID-19 deaths (6 vaccinated, 11 unvaccinated) and 8209 SARS-CoV-2 infections. Absolute risk of COVID-19 deaths was 0.003%. rVE estimates for COVID-19 deaths and reinfections exceeded 75% until the end of 2021 but decreased substantially with extended follow-up. The risk of non-COVID-19 death was lower in those vaccinated versus unvaccinated.

Conclusions

First and second SARS-CoV-2 vaccine doses appear effective in the short-term, but with diminishing effectiveness over time. The extremely low COVID-19 mortality, regardless of vaccination, indicates strong protection of previous infection against COVID-19 death. Lower non-COVID-19 mortality in the vaccinated population might suggest a healthy vaccinee bias.

A Novel Anti-nucleocapsid Antibody Avidity Method for Identifying SARS-CoV-2 Reinfections

Detecting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reinfections is challenging with current serology assays and is further complicated by the marked decrease in routine viral testing practices as viral transmission increased during Omicron. Here, we provide proof-of-principle that high-avidity anti-nucleocapsid (N) antibodies detects reinfections after a single infection with higher specificity (85%; 95% confidence interval [95% CI], 80%-90%) compared to anti-N antibody levels (72%; 95% CI, 66%-79%) in a vaccinated cohort. This method could be used to retroactively investigate the epidemiology and incremental long-term health consequences of SARS-CoV-2 reinfections.

Tracking temporal variations of fatality and symptomology correlated with COVID-19 dominant variants and vaccine effectiveness in the United States

Introduction

We described how COVID-19 fatality and symptoms varied by dominant variant and vaccination in the US.

Methods

Using the Restricted Access Dataset from the US CDC (1/1/2020-10/20/2022), we conducted a cross-sectional study assessing differences in COVID-19 deaths, severity indicators (hospitalization, ICU, pneumonia, abnormal X-ray, acute respiratory distress syndrome, mechanical ventilation) and 12 mild symptoms by dominant variant/vaccination periods using logistic regression after controlling for confounders.

Results

We found the highest fatality during the dominant periods of Wild (4.6%) and Delta (3.4%). Most severe symptoms appeared when Delta was dominant (Rate range: 2.0-9.4%). Omicron was associated with higher mild symptoms than other variants. Vaccination showed consistent protection against death and severe symptoms for most variants (Risk Ratio range: 0.41-0.93). Boosters, especially the second, provided additional protection, reducing severe symptoms by over 50%.

Discussion

This dataset may serve as a useful tool to monitor temporospatial changes of fatality and symptom for case management and surveillance.

Effectiveness of COVID-19 Vaccines in People with Severe Mental Illness: A Systematic Review and Meta-Analysis

Prior to the introduction of COVID-19 vaccines, patients with severe mental illness (SMI) were at greater risk of COVID-19-related outcomes than the general population. It is not yet clear whether COVID-19 vaccines have reduced the risk gap. We systematically searched nine international databases and three Chinese databases to identify relevant studies from December 2020 to December 2023 to compare the risk of COVID-19-related outcomes for SMI patients to those without SMI after vaccination. Random effects meta-analysis was performed to estimate the pooled odds ratio (OR) with 95% confidence intervals (CI). Subgroup analysis, sensitivity analysis, and publication bias analysis were conducted with R software 4.3.0. A total of 11 observational studies were included. Compared with controls, SMI patients were associated with a slightly increased risk of infection (pooled OR = 1.10, 95% CI, 1.03-1.17, I2 = 43.4%), while showing a 2-fold higher risk of hospitalization (pooled OR = 2.66, 95% CI, 1.13-6.22, I2 = 99.6%), even after both groups have received COVID-19 vaccines. Limited evidence suggests a higher mortality risk among SMI patients compared to controls post vaccination, but the findings did not reach statistical significance. SMI patients remain at increased risk compared to their peers in COVID-19-related outcomes even after vaccination. Vaccination appears an effective approach to prevent severe COVID-19 illness in SMI patients, and actions should be taken by healthcare providers to improve vaccination coverage in these vulnerable groups.

SARS-COV-2 breakthrough infection and its covariates among healthcare providers of a hospital in Bangladesh during the omicron wave

Introduction

Breakthrough infection by SARS-COV-2 virus among vaccinated individuals has been reported from all over the world and it has created a substantial challenge in designing strategies to live with the virus in the post-pandemic era. Factors affecting the extent and nature of breakthrough infection are still not fully understood and those are known to vary depending on host and agent factors. Health Care Workers (HCWs), especially in hospital settings, are front-liners in combating the epidemic and, consequently, they are more vulnerable to breakthrough infection by SARS-COV-2. Like most of the countries of the world, Bangladesh went through several waves of COVID-19 and the last (3rd wave) was the widespread Omicron wave during the winter of 2022. HCWs in Bangladesh have been disproportionately affected by the virus. Under this context, the aim of the present study was to explore breakthrough infection (BTI) and its host-related covariates among HCWs of a COVID-dedicated city-based hospital during the Omicron wave in Bangladesh.

Materials and methods

An observational cross-sectional study was conducted on 267 HCWs of the Narayanganj Tertiary (300-bed) hospital during February-March 2022 which coincided with the terminal part of the 3rd wave. Data were collected by trained Field Assistants using Interviewer-administered Data Collection Forms with Questionnaires as instruments. Previous COVID-19 status (any time after the onset of the pandemic and within last 3 months) was explored by the history of specific symptoms as well as by the confirmatory rtPCR test reports from DGHS approved laboratories Anti-nucleocapsid antibody (Anti-N-Ab) in venous blood samples, assayed by a chemiluminescent ELISA technique, was used as a seroprevalence-based marker of breakthrough infection during the preceding few months. Data were analyzed by bivariate as well as multivariate statistics using the IBM-SPSS software.

Results

The median age (range) of the HCWs was 38 (21-65) years; Body Mass Index (BMI, kg/m2) 25 (15-49); and Waist-Hip Ratio (WHR) was 0.92 (0.46-1.21). The male subjects had significantly higher median age (p = 0.01) and higher WHR (p = 0.001) as compared to the female subjects. As per the BMI category, subjects with overweight and obesity constituted 83.3 % of the male subjects as compared to 61.6 % of the female subjects (p = 0.001). The time lapse between receiving of 3rd dose and blood sampling was significantly higher among females compared to males (median days 60 vs 49, p < 0.02) indicating earlier vaccination with 1st booster dose among females. A proportion of 51.85 % male and 49.68 % female subjects showed Anti-N-Ab positivity; there was no significant difference between the gender groups. Also, there was no significant difference among male and female subjects regarding the Ab levels. On Spearman correlation analysis, a tendency of association of WHR with Ab level was observed among the male subjects; however, the association did not show statistical significance (p = 0.09). On binary logistic regression Ab positivity was found to be independently associated with WHR (p = 0.03), and prior SARS-COV-2 infection within the last 3 months (p = 0.02) among males. When all the subjects were considered together, COVID symptom positivity during the last 3 months (p = 0.067) and receiving the 1st booster dose (p = 0.07) showed a tendency of association with Ab positivity. On multiple regression analysis, Ab levels showed a negative association with WHR (p = 0.035) among males.

Conclusions

More than 50 % of the vaccinated hospital-based HCWs in Bangladesh suffered from BTI during the winter of 2022 when the Omicron wave (the 3rd wave) of COVID-19 was at its peak. The data also indicate that overweight and obesity are major host-related risk factors underlying BTI. Inadequate coverage by a booster dose seems to be another determinant of BTI and the level of immune response in this population.

Investigation of SARS-CoV-2 IgG Binding Capability to Variants of the SARS-CoV-2 Virus

The SARS-CoV-2 pandemic has confirmed that the ability to rapidly mutate may be extremely beneficial for a virus. Not long after the first wave, new variants emerged with altered infectivity, disease severity, and mortality. These new strains most notably had numerous mutations of the spike (S) protein, a surface protein responsible for binding to and entering the host cell. The Delta and Omicron strains demonstrated increased immune evasion and improved binding affinity to the host cell receptor, angiotensin-converting enzyme 2 (ACE2). This study examines the ability of wild-type SARS-CoV-2 IgG to bind Delta and Omicron antigens, as well as their functional binding capabilities to two different S-ACE2 complexes. Twenty SARS-CoV-2 positive samples from patients who had recovered from infection with ancestral SARS-CoV-2 in the first wave of COVID-19 and 10 pre-pandemic control samples were studied. SARS-CoV-2 exposed patients showed significantly higher levels of IgG to SARS-CoV-2 S1/RBD (p < 0.001), N protein (p < 0.001), and Omicron spike variant (p = 0.01), but not to Delta spike variant (p = 0.966) when compared with controls. Furthermore, patient samples showed significantly greater inhibition of SARS-CoV-2 S1/RBD and E484K spike to ACE2 binding (p < 0.001 and p = 0.015, respectively). Conversely, there was no correlation between the binding inhibition of S1/RBD and E484K spike to ACE2 receptor. This study shows there is considerable cross-reactivity of IgG generated by wild-type SARS-CoV-2 infection to the Delta and Omicron variants.

Evaluating the impact of extended dosing intervals on mRNA COVID-19 vaccine effectiveness in adolescents

BACKGROUND

Extending the dosing interval of a primary series of mRNA COVID-19 vaccination has been employed to reduce myocarditis risk in adolescents, but previous evaluation of impact on vaccine effectiveness (VE) is limited to risk after second dose.

METHODS

We quantified the impact of the dosing interval based on case notifications and vaccination uptake in Hong Kong from January to April 2022, based on calendar-time proportional hazards models and matching approaches.

RESULTS

We estimated that the hazard ratio (HR) and odds ratio (OR) of infections after the second dose for extended (28 days or more) versus regular (21-27 days) dosing intervals ranged from 0.86 to 0.99 from calendar-time proportional hazards models, and from 0.85 to 0.87 from matching approaches, respectively. Adolescents in the extended dosing groups (including those who did not receive a second dose in the study period) had a higher hazard of infection than those with a regular dosing interval during the intra-dose period (HR 1.66; 95% CI 1.07, 2.59; p = 0.02) after the first dose.

CONCLUSIONS

Implementing an extended dosing interval should consider multiple factors including the degree of myocarditis risk, the degree of protection afforded by each dose, and the extra protection achievable using an extended dosing interval.

Superspreading of SARS-CoV-2 at a choir rehearsal in Finland-A computational fluid dynamics view on aerosol transmission and patient interviews

INTRODUCTION

COVID-19 pandemic has highlighted the role of aerosol transmission and the importance of superspreading events. We analyzed a choir rehearsal in November 2020, where all participants, except one who had recently earlier recovered from COVID-19, were infected. We explore the risk factors for severe disease in this event and model the aerosol dispersion in the rehearsal room.

MATERIALS AND METHODS

Characteristics of participants were collected by interviews and supplemented with patient records. A computational simulation of aerosol distribution in the rehearsal room and the efficacy of potential safety measures was conducted using the Large-Eddy Simulation approach. Infection risk was studied by analyzing quanta emission and exposure with the Wells-Riley equation.

RESULTS

The simulation showed that airborne transmission likely explains this mass contagion event. Every singer was exposed to the virus in only 5 min from the beginning of the rehearsal, and maximum concentration levels were reached at 20 min the concentration levels started to approach a steady state after 20 min. Although concentration differences existed in the room, risk levels near (1 m) and far (5 m) from the aerosol source were similar for certain singers. Modeling indicated infection risk levels of 70-100% after one hour; the risk would have been considerably reduced by wearing high-filtration respirators. Age and pre-existing comorbidities predicted more severe disease. The high incidence of illness may be partly attributed to the relatively high median age of individuals. Additionally, those admitted to the hospital had multiple underlying health conditions that predispose them to more severe disease.

CONCLUSIONS

Airborne transmission and indoor space can explain this mass exposure event. High-filtration respirators could have prevented some infections. The importance of safety distances diminishes the longer the indoor event. The concept of safety distance is challenging, as our study suggests that long range airborne transmission may occur in indoor events with extended duration. We encourage informing the public, especially persons at risk, of safety measures during epidemics.

Enhancing COVID-19 Vaccination Awareness and Uptake in the Post-PHEIC Era: A Narrative Review of Physician-Level and System-Level Strategies

Following the World Health Organization's declaration that the COVID-19 pandemic is no longer a public health emergency of international concern (PHEIC), COVID-19 remains an ongoing threat to human health and healthcare systems. Vaccination plays a crucial role in reducing the disease's incidence, mitigating its severity, and limiting transmission, contributing to long-term public health resilience. However, incomplete vaccination coverage and vaccine hesitancy exist. This narrative review investigates strategies at the system and physician levels aimed at sustaining awareness and uptake of COVID-19 vaccination in a post-PHEIC era. Through an examination of the existing literature, this review explores the effectiveness of diverse approaches utilized by healthcare systems and individual providers. These approaches address every component of the 5C model of vaccine hesitancy: confidence, complacency, constraints/convenience, calculation, and collective responsibility. Physician-level approaches include appropriate message framing, persuasive communication containing safety and personal/social benefit information, sharing of personal stories, creating a safe space for discussion, harnessing co-administration with annual influenza vaccines, and use of decision aids and visual messages. System-level approaches include messaging, mass media for health communication, on-site vaccine availability, pharmacist delivery, healthcare protocol integration, incentives, and chatbot use.

Association Between Hospital Type and Resilience During COVID-19 Caseload Stress : A Retrospective Cohort Study

BACKGROUND

Imbalances between hospital caseload and care resources that strained U.S. hospitals during the pandemic have persisted after the pandemic amid ongoing staff shortages. Understanding which hospital types were more resilient to pandemic overcrowding-related excess deaths may prioritize patient safety during future crises.

OBJECTIVE

To determine whether hospital type classified by capabilities and resources (that is, extracorporeal membrane oxygenation [ECMO] capability, multiplicity of intensive care unit [ICU] types, and large or small hospital) influenced COVID-19 volume-outcome relationships during Delta wave surges.

DESIGN

Retrospective cohort study.

SETTING

620 U.S. hospitals in the PINC AI Healthcare Database.

PARTICIPANTS

Adult inpatients with COVID-19 admitted July to November 2021.

MEASUREMENTS

Hospital-months were ranked by previously validated surge index (severity-weighted COVID-19 inpatient caseload relative to hospital bed capacity) percentiles. Hierarchical models were used to evaluate the effect of log-transformed surge index on the marginally adjusted probability of in-hospital mortality or discharge to hospice. Effect modification was assessed for by 4 mutually exclusive hospital types.

RESULTS

Among 620 hospitals recording 223 380 inpatients with COVID-19 during the Delta wave, there were 208 ECMO-capable, 216 multi-ICU, 36 large (≥200 beds) single-ICU, and 160 small (<200 beds) single-ICU hospitals. Overall, 50 752 (23%) patients required admission to the ICU, and 34 274 (15.3%) died. The marginally adjusted probability for mortality was 5.51% (95% CI, 4.53% to 6.50%) per unit increase in the log surge index (strain attributable mortality = 7375 [CI, 5936 to 8813] or 1 in 5 COVID-19 deaths). The test for interaction showed no difference (P = 0.32) in log surge index-mortality relationship across 4 hospital types. Results were consistent after excluding transferred patients, restricting to patients with acute respiratory failure and mechanical ventilation, and using alternative strain metrics.

LIMITATION

Residual confounding.

CONCLUSION

Comparably detrimental relationships between COVID-19 caseload and survival were seen across all hospital types, including highly advanced centers, and well beyond the pandemic's learning curve. These lessons from the pandemic heighten the need to minimize caseload surges and their effects across all hospital types during public health and staffing crises.

PRIMARY FUNDING SOURCE

Intramural Research Program of the National Institutes of Health Clinical Center.

Data-driven mathematical modeling approaches for COVID-19: A survey

In this review, we successively present the methods for phenomenological modeling of the evolution of reported and unreported cases of COVID-19, both in the exponential phase of growth and then in a complete epidemic wave. After the case of an isolated wave, we present the modeling of several successive waves separated by endemic stationary periods. Then, we treat the case of multi-compartmental models without or with age structure. Eventually, we review the literature, based on 260 articles selected in 11 sections, ranging from the medical survey of hospital cases to forecasting the dynamics of new cases in the general population. This review favors the phenomenological approach over the mechanistic approach in the choice of references and provides simulations of the evolution of the number of observed cases of COVID-19 for 10 states (California, China, France, India, Israel, Japan, New York, Peru, Spain and United Kingdom).

First SARS-CoV-2 Omicron infection as an effective immune booster among mRNA vaccinated individuals: final results from the first phase of the PRIBIVAC randomised clinical trial

BACKGROUND

Understanding how SARS-CoV-2 breakthrough infections impacts the breadth of immune responses against existing and pre-emergent SARS-CoV-2 strains is needed to develop an evidence-based long-term immunisation strategy.

METHODS

We performed a randomised, controlled trial to assess the immunogenicity of homologous (BNT162b2) versus heterologous (mRNA-1273) booster vaccination in 100 BNT162b2-vaccinated infection-naïve individuals enrolled from October 2021. Post hoc analysis was performed to assess the impact of SARS-CoV-2 infection on humoral and cellular immune responses against wild-type SARS-CoV-2 and/or Omicron subvariants.

FINDINGS

93 participants completed the study at day 360. 71% (66/93) of participants reported first SARS-CoV-2 Omicron infection by the end of the study with similar proportions of infections between homologous and heterologous booster groups (72.3% [34/47] vs 69.6% [32/46]; p = 0.82). Mean wildtype SARS-CoV-2 anti-S-RBD antibody level was significantly higher in heterologous booster group compared with homologous group at day 180 (14,588 IU/mL; 95% CI, 10,186-20,893 vs 7447 IU/mL; 4646-11,912; p = 0.025). Participants who experienced breakthrough infections during the Omicron BA.1/2 wave had significantly higher anti-S-RBD antibody levels against wildtype SARS-CoV-2 and antibody neutralisation against BA.1 and pre-emergent BA.5 compared with infection-naïve participants. Regardless of hybrid immunity status, wildtype SARS-CoV-2 anti-S-RBD antibody level declined significantly after six months post-booster or post-SARS-CoV-2 infection.

INTERPRETATION

Booster vaccination with mRNA-1273 was associated with significantly higher antibody levels compared with BNT162b2. Antibody responses are narrower and decline faster among uninfected, vaccinated individuals. Boosters may be more effective if administered shortly before infection outbreaks and at least six months after last infection or booster.

FUNDING

Singapore NMRC, USFDA, MRC.

Latent Class Analysis Reveals, in patient profiles, COVID-19-related better prognosis by calcifediol treatment than glucocorticoids

Calcifediol and glucocorticoids have been repositioned for the treatment of COVID-19 and may reduce severity, the need for intensive care unit admission and death.

OBJECTIVE

to identify class or profiles of patients hospitalized and treated with COVID-19 pneumonia using latent class clustering methods to assess the clinical and prognostic relevance of the resulting patients' profiles. Poor prognosis was defined as death or need for ICU admission, good prognosis, the opposite. With special interest in differential responses to calcifediol.

SETTING

Reina Sofia University Hospital, Córdoba Spain.

PATIENTS

Retrospective observational cohort study of patients admitted for COVID-19.

CLINICALTRIALS

gov public database (NCT05819918).

INCLUSION CRITERIA

(i) Age ≥ 18 and ≤ 90 years, (ii) Pneumonia characterized by the presence of infiltrates on chest X-ray or CT scan, (iii) SARS-CoV-2 infection, confirmed, and (iv) CURB Scale 65 >1.

DESIGN

Latent class analysis, for obtaining homogeneous clusters, without specifying a priori the belonging group, and selecting the optimal number of clusters by minimizing information criteria. Evaluating the differences between groups for each variable by means of chi-square, Fisher's exact test and Kruskal-Wallis test.

RESULTS

707 patients hospitalized from 10 March 2020 until 4 March 2022 were included. For the treatment variable, differences were found between class 3 (60 % treated with calcifediol only) and classes 1 (less than 1 % calcifediol only vs. 82 % treated with both), 2 (less than 1 % calcifediol only vs. 82 % treated with both) and 4 (1 % calcifediol only vs. 84 % treated with both). Class 3, (60 % with calcifediol), had a significantly better prognosis compared to patients treated with glucocorticoids alone (OR: 15.2, 95 % CI: [3.73-142], p<0.001) or no treatment (OR: 7.38, 95 % CI: [2.63-30.2], p<0.001).

CONCLUSIONS

our real-life study shows that calcifediol treatment significantly reduces the need for ICU admission and improved prognosis in patients hospitalized for COVID-19 pneumonia, especially in the profile of patients receiving it without glucocorticoids.

Risk of COVID-19 in Children throughout the Pandemic and the Role of Vaccination: A Narrative Review

At the beginning of the coronavirus disease 2019 (COVID-19) pandemic, persons ≥65 years of age and healthcare personnel represented the most vulnerable groups with respect to risk of infection, severe illness, and death. However, as the pandemic progressed, there was an increasingly detrimental effect on young children and adolescents. Severe disease and hospitalization increased over time in pediatric populations, and containment measures created substantial psychosocial, educational, and economic challenges for young people. Vaccination of children against COVID-19 has been shown to reduce severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections and severe outcomes in pediatric populations and may also help to prevent the spread of variants of concern and improve community immunity. This review discusses the burden of COVID-19 on children throughout the pandemic, the role of children in disease transmission, and the impact of COVID-19 vaccination.

Myocarditis incidence and hospital mortality from 2007 to 2022: insights from a nationwide registry

OBJECTIVES

To investigate the burden of disease of myocarditis in Germany and identify similarities and differences in myocarditis with or without COVID-19.

METHODS

All patients hospitalized with myocarditis in Germany were included in this nationwide retrospective analysis. Data were retrieved from the Federal Statistical Office of Germany (DESTATIS) for the years from 2007 to 2022. The primary endpoint was hospital mortality.

RESULTS

A total of 88,159 patients hospitalized with myocarditis were analyzed. Annual cases increased from 5100 in 2007 to 6593 in 2022 (p < 0.001 for trend) with higher incidence during winter months. Incidence per 100,000 inhabitants was 6.2 in 2007 rising to 7.8 in 2022 (p < 0.001 for trend). Hospital mortality remained constant at an average of 2.44% (p = 0.164 for trend). From 2020 to 2022, 1547/16,229 (9.53%) patients were hospitalized with both, myocarditis and COVID-19 (incidence 0.62/100,000 inhabitants and 180/100,000 hospitalizations with COVID-19). These patients differed significantly in most patient characteristics and had a higher rate of hospital mortality compared to myocarditis without COVID-19 (12.54% vs. 2.26%, respectively, p < 0.001).

CONCLUSIONS

Myocarditis hospitalizations were slowly rising over the past 16 years with hospital mortality remaining unchanged. Incidence of hospitalizations with combined myocarditis and COVID-19 was low, but hospital mortality was high.

Post-COVID anxiety, depression, and quality of life among Egyptian hemodialysis patients

INTRODUCTION

This study examined the impact of Coronavirus disease 2019  on anxiety, depression, and health-related quality of life (HRQOL) among Egyptian hemodialysis (HD) patients.

METHODS

This multicenter cross-sectional study was carried out in Egypt in the years 2021-2022, where 300 HD patients from four HD centers were allocated into two groups: post-COVID and non-COVID. The Hospital Anxiety and Depression Scale (HADS) and the Kidney Disease QOL-36 questionnaire were used to assess anxiety, depression, and QOL of the included patients.

RESULTS

In the post-COVID group, abnormal and borderline cases of anxiety and depression were detected in 38.6% and 62.5% of patients, respectively, with no statistically significant difference between both groups. The post-COVID group showed higher work status and lower sexual and physical functioning, which correlated negatively with anxiety and depression scores.

CONCLUSION

Past-COVID infection did not influence depression and anxiety symptoms in HD patients. Sexual and physical functioning were more affected among COVID-survivors.

Modeling Nursing Home Harms From COVID-19 Staff Furlough Policies

Importance

Current guidance to furlough health care staff with mild COVID-19 illness may prevent the spread of COVID-19 but may worsen nursing home staffing shortages as well as health outcomes that are unrelated to COVID-19.

Objective

To compare COVID-19-related with non-COVID-19-related harms associated with allowing staff who are mildly ill with COVID-19 to work while masked.

Design, Setting, and Participants

This modeling study, conducted from November 2023 to June 2024, used an agent-based model representing a 100-bed nursing home and its residents, staff, and their interactions; care tasks; and resident and staff health outcomes to simulate the impact of different COVID-19 furlough policies over 1 postpandemic year.

Exposures

Simulating increasing proportions of staff who are mildly ill and are allowed to work while wearing N95 respirators under various vaccination coverage, SARS-CoV-2 transmissibility and severity, and masking adherence.

Main Outcomes and Measures

The main outcomes were staff and resident COVID-19 cases, staff furlough days, missed care tasks, nursing home resident hospitalizations (related and unrelated to COVID-19), deaths, and costs.

Results

In the absence of SARS-CoV-2 infection in the study's 100-bed agent-based model, nursing home understaffing resulted in an annual mean (SD) 93.7 (0.7) missed care tasks daily (22.1%), 38.0 (7.6) resident hospitalizations (5.2%), 4.6 (2.2) deaths (0.6%), and 39.7 (19.8) quality-adjusted life years lost from non-COVID-19-related harms, costing $1 071 950 ($217 200) from the Centers for Medicare & Medicaid Services (CMS) perspective and $1 112 800 ($225 450) from the societal perspective. Under the SARS-CoV-2 Omicron variant conditions from 2023 to 2024, furloughing all staff who tested positive for SARS-CoV-2 was associated with a mean (SD) 326.5 (69.1) annual furlough days and 649.5 (95% CI, 593.4-705.6) additional missed care tasks, resulting in 4.3 (95% CI, 2.9-5.9) non-COVID-19-related resident hospitalizations and 0.7 (95% CI, 0.2-1.1) deaths, costing an additional $247 090 (95% CI, $203 160-$291 020) from the CMS perspective and $405 250 (95% CI, $358 550-$451 950) from the societal perspective. Allowing 75% of staff who were mildly ill to work while masked was associated with 5 additional staff and 5 additional resident COVID-19 cases without added COVID-19-related hospitalizations but mitigated staffing shortages, with 475.9 additional care tasks being performed annually, 3.5 fewer non-COVID-19-related hospitalizations, and 0.4 fewer non-COVID-19-related deaths. Allowing staff who were mildly ill to work ultimately saved an annual mean $85 470 (95% CI, $41 210-$129 730) from the CMS perspective and $134 450 (95% CI, $86 370-$182 540) from the societal perspective. These results were robust to increased vaccination coverage, increased nursing home transmission, increased importation of COVID-19 from the community, and failure to mask while working ill.

Conclusion and Relevance

In this modeling study of staff COVID-19 furlough policies, allowing nursing home staff to work with mild COVID-19 illness was associated with fewer resident harms from staffing shortages and missed care tasks than harms from increased COVID-19 transmission, ultimately saving substantial direct medical and societal costs.

Immune responses in COVID-19 patients: Insights into cytokine storms and adaptive immunity kinetics

SARS-CoV-2 infection can trigger cytokine storm in some patients, which characterized by an excessive production of cytokines and chemical mediators. This hyperactive immune response may cause significant tissue damage and multiple organ failure (MOF). The severity of COVID-19 correlates with the intensity of cytokine storm, involving elements such as IFN, NF-κB, IL-6, HMGB1, etc. It is imperative to rapidly engage adaptive immunity to effectively control the disease progression. CD4+ T cells facilitate an immune response by improving B cells in the production of neutralizing antibodies and activating CD8+ T cells, which are instrumental in eradicating virus-infected cells. Meanwhile, antibodies from B cells can neutralize virus, obstructing further infection of host cells. In individuals who have recovered from the disease, virus-specific antibodies and memory T cells were observed, which could confer a level of protection, reducing the likelihood of re-infection or attenuating severity. This paper discussed the roles of macrophages, IFN, IL-6 and HMGB1 in cytokine release syndrome (CRS), the intricacies of adaptive immunity, and the persistence of immune memory, all of which are critical for the prevention and therapeutic strategies against COVID-19.

SARS-CoV-2 reinfection rate before and after VOC Omicron emergence: a retrospective study in Brazil

SARS-COV-2 reinfection has been reported worldwide, although its rate remains unclear. VOC Omicron's emergence and its sub-variants led to an unprecedented number of COVID-19 cases in several countries, raising concerns regarding reinfection rates. 324,979 RT-qPCR-confirmed positive cases (72.57% from Minas Gerais State) diagnosed between April 1, 2020, and August 31, 2022, at the Hermes Pardini, Grupo Fleury (Brazil) were used to estimate the reinfection rate. Instances of reinfection were characterized by two positive tests occurring with a minimum interval of 60 days. We identified 11,669 cases of reinfection. The states of Minas Gerais, São Paulo, Rio de Janeiro and Goiás represented almost 41% of the reinfections. Up until epidemiological week 46 of 2020, only 14 cases of reinfection were recorded. The majority of reinfections, totalling 6,316 cases, were detected during the circulation period of the Omicron and its sublineages BA.1 and BA.2. Another 4,273 reinfections occurred during the circulation period of sublineages BA.4 and BA.5, revealing two distinct groups of observations. The first group comprised cases of reinfection with a shorter time interval (two infections within a period of up to 200 days), while the second group was associated with a longer time interval (two infections within a period of more than 500 days). The reinfection rate during this period was nearly 8%, which is six times higher than the rate observed at the beginning of the study. In conclusion, our study underscores the dynamic nature of SARS-CoV-2 reinfections and their correlation with emerging variants such as Omicron.

Household transmission of Omicron variant of SARS-CoV-2 under conditions of hybrid immunity-a prospective study in Germany

PURPOSE

We investigated the protection offered by vaccinations and previous infections for the household transmission of Omicron variant of SARS-CoV-2.

METHODS

34,666 participants of the German DigiHero cohort study with two or more household members were invited to a prospective household transmission study between June and December 2022. In case of a positive SARS-CoV-2 test in a household, symptom diaries were completed for at least 14 days. Dry blood spots (DBS) were taken from all household members at the beginning and six to eight weeks later. DBS were analyzed for SARS-CoV-2 antibodies.

RESULTS

1191 individuals from 457 households participated. The risk of acquiring a SARS-CoV-2 infection decreased with higher S-titer levels at the time of exposure (from 80% at titer of 0 binding antibody units (BAU)/ml to 20% at titer of 3000 BAU/ml) and increased linearly with the time since vaccination/previous infection (20% for less than one month to 80% at one year). Transmission probability was also reduced when the symptoms of the primary case were mild and if preventive measures were implemented.

CONCLUSION

Vaccinations/previous infections offer a high protection against infection with the Omicron variant for a few months only, supporting the notion of seasonal circulation of the virus.

Breakthrough COVID-19 Infections after Booster SARS-CoV-2 Vaccination in a Greek Cohort of People Living with HIV during the Delta and Omicron Waves

INTRODUCTION

Currently approved SARS-CoV-2 vaccines have been proven effective in protecting against severe COVID-19; however, they show variable efficacy against symptomatic infection and disease transmission. We studied the breakthrough COVID-19 infection (BTI) after booster vaccination against SARS-CoV-2 in people living with HIV (PWH).

METHODS

This was a retrospective, single-center, descriptive cohort study involving PWH, who were followed in the HIV Clinic of "Attikon" University Hospital in Athens, Greece. A BTI was defined as a case of laboratory-confirmed COVID-19 occurring at least 14 days after the third (booster) vaccine dose.

RESULTS

We studied 733 PWH [males: 89%, mean age: 45.2 ± 11.3 years, mean BMI: 26.1 ± 4.1, HIV stage at diagnosis (CDC classification): A/B/C = 80/9/11%, MSM: 72.6%] with well-controlled HIV infection. At least one comorbidity was recorded in 54% of cases. A history of ≥1 vaccination was reported by 90%, with 75% having been vaccinated with ≥3 vaccines. Four hundred and two (55%) PWH had a history of COVID-19 and 302 (41.2%) had a BTI, with only 15 (3.7%) needing hospitalization. Only one patient was admitted to the ICU, and no death was reported. Regarding BTI after booster dose, increased age (OR = 0.97, 95% CI: 0.96-0.99, per 1-year increase), and COVID-19 infection prior to booster dose (OR = 0.38, 95% CI: 0.21-0.68) were associated with a lower likelihood for BTI, whereas higher BMI (OR = 1.04, 95% CI: 1.01-1.08) and MSM as a mode of HIV transmission were associated with increased risk (OR = 2.59, 95% CI: 1.47-4.56). The incidence rate of total COVID-19 and BTI followed the epidemic curve of the general population, with the highest incidence recorded in June 2022.

CONCLUSIONS

A significant proportion of PWH with well-controlled HIV infection experienced a BTI, with the majority of them having mild infection. These data, which include the period of Omicron variant predominance, confirm the importance of vaccination in the protection against severe COVID-19.

The Transmission of SARS-CoV-2 from COVID-19-Diagnosed People to Their Pet Dogs and Cats in a Multi-Year Surveillance Project

Recent emerging zoonotic disease outbreaks, such as that of SARS-CoV-2, have demonstrated the need for wider companion animal disease surveillance. We tested 1000 dogs and cats belonging to employees of a US veterinary hospital network that were exposed to human COVID-19 cases in the household between 1 January 2020 and 10 March 2022 for SARS-CoV-2 and surveyed their owners about clinical signs and risk factors. The seropositivity was 33% for 747 dogs and 27% for 253 cats. Pet seropositivity correlated with the US human case rates over time, exhibiting peaks corresponding with the major COVID-19 surges. Antibodies persisted longer than previously documented (828 days in dogs; 650 days in cats). Increasing age and duration of proximity to infected people were associated with increased seropositivity in dogs but not cats. Cats were more likely to have clinical signs, but an association between seropositivity and the presence of clinical signs was not found in either species.

Risk factors for COVID-19 hospitalisation after booster vaccination during the Omicron period: A French nationwide cohort study

BACKGROUND

In spite of major effectiveness, a residual risk after COVID-19 primary vaccination was identified, in particular, for vulnerable individuals of advanced age or with comorbidities. Less is known about the Omicron period in people protected by a booster dose. We aimed to identify the characteristics associated with severe COVID-19 during the Omicron period in a population that had received a booster dose in France and to compare differences with the previous periods of the pandemic.

METHODS

This study was carried out using the French national COVID-19 vaccination database (VAC-SI) coupled with the National Health Data System (SNDS). Individuals aged 12 years or over who received at least one booster dose were identified. Associations between socio-demographic and clinical characteristics and the risk of COVID-19 hospitalisation occurring at least 14 days after receiving a third dose of vaccine during the period of Omicron predominance, i.e., from 1 January 2022 to 10 November 2022, were assessed using Cox proportional hazard models adjusted for age, sex, time since booster dose and vaccination schedule. Analyses were performed overall and by sub-period of circulation of the strains BA.1, BA.2, and BA.4/BA.5, defined as periods where the main sub-variant accounted for more than 80 % of genotyped samples.

FINDINGS

In total, 35,640,387 individuals received a booster dose (mean follow-up of 291 days) and 73,989 were hospitalised for COVID-19 during the total period. Older age (aHR 20.5 95 % CI [19.6-21.5] for 90 years of age or older versus 45-54 years of age), being male (aHR 1.52 [1.50-1.55]), and social deprivation (aHR 1.33 [1.30-1.37] for the most deprived areas versus the least deprived) were associated with an increased risk of hospitalisation for COVID-19. Most of the chronic diseases considered were also positively associated with a residual risk, in particular, cystic fibrosis (aHR 9.83 [7.68-12.56]), active lung cancer (aHR 3.26 [3.06-3.47]), chronic dialysis (aHR 3.79 [3.49-4.11]), psychological and neurodegenerative diseases (more markedly than during the periods of circulation of the alpha and delta variants), and organ transplantation. The use of immunosuppressants was also associated with an increased risk (aHR 2.24 [2.14-2.35], including oral corticosteroids aHR (2.58 [2.50-2.67]).

CONCLUSION

Despite an effective booster and a generally less virulent circulating variant, a residual risk of severe COVID-19 still exists in vulnerable populations, especially those with neurological disorders.

Integrate-and-fire model of disease transmission

We create an epidemiological susceptible-infected-susceptible model of disease transmission using integrate-and-fire nodes on a network, allowing memory of previous interactions and infections. Agents in the network sum infectious matter from their nearest neighbors at every time step, until they exceed their infection threshold, at which point they "fire" and become infected for as long as the recovery time. The model has memory of previous interactions by tracking the amount of infectious matter carried by agents as well as just binary infected or susceptible states, and the model has memory of previous infections by modeling immunity as increasing the infection threshold after recovery. Creating a simulation of the model on networks with a power-law degree distribution and homogeneous agent parameters, we find a single strain version of the model matches well with the England COVID-19 case data, with a root-mean-squared error of 0.014%. A simulation of a multistrain version of the model (where there is cross-strain immunity) matches well with the influenza strain A and strain B case numbers in Canada, with a root-mean-squared error of 0.002% and 0.0012%, respectively, though due to the coupling in the model, both strains peak in phase. Since the dynamics of the model successfully capture real-life transmission dynamics, we test interventions to study their effect on case numbers, with both quarantining and social gathering restrictions lowering the peak. Since the model has memory, the stricter the intervention, the higher the secondary peak when the restriction is removed, showing that interventions change only the shape of the curves and not the overall number infected in the population.

COVID-19 Vaccine Effectiveness in Autumn and Winter 2022 to 2023 Among Older Europeans

Importance

In the context of emerging SARS-CoV-2 variants or lineages and new vaccines, it is key to accurately monitor COVID-19 vaccine effectiveness (CVE) to inform vaccination campaigns.

Objective

To estimate the effectiveness of COVID-19 vaccines administered in autumn and winter 2022 to 2023 against symptomatic SARS-CoV-2 infection (with all circulating viruses and XBB lineage in particular) among people aged 60 years or older in Europe, and to compare different CVE approaches across the exposed and reference groups used.

Design, Setting, and Participants

This case-control study obtained data from VEBIS (Vaccine Effectiveness, Burden and Impact Studies), a multicenter study that collects COVID-19 and influenza data from 11 European sites: Croatia; France; Germany; Hungary; Ireland; Portugal; the Netherlands; Romania; Spain, national; Spain, Navarre region; and Sweden. Participants were primary care patients aged 60 years or older with acute respiratory infection symptoms who were recruited at the 11 sites after the start of the COVID-19 vaccination campaign from September 2022 to August 2023. Cases and controls were defined as patients with positive and negative, respectively, reverse transcription-polymerase chain reaction (RT-PCR) test results.

Exposures

The exposure was COVID-19 vaccination. The exposure group consisted of patients who received a COVID-19 vaccine during the autumn and winter 2022 to 2023 vaccination campaign and 14 days or more before symptom onset. Reference group included patients who were not vaccinated during or in the 6 months before the 2022 to 2023 campaign (seasonal CVE), those who were never vaccinated (absolute CVE), and those who were vaccinated with at least the primary series 6 months or more before the campaign (relative CVE). For relative CVE of second boosters, patients receiving their second booster during the campaign were compared with those receiving 1 booster 6 months or more before the campaign.

Main Outcomes and Measures

The outcome was RT-PCR-confirmed, medically attended, symptomatic SARS-CoV-2 infection. Four CVE estimates were generated: seasonal, absolute, relative, and relative of second boosters. CVE was estimated using logistic regression, adjusting for study site, symptom onset date, age, chronic condition, and sex.

Results

A total of 9308 primary care patients were included, with 1687 cases (1035 females; median [IQR] age, 71 [65-79] years) and 7621 controls (4619 females [61%]; median [IQR] age, 71 [65-78] years). Within 14 to 89 days after vaccination, seasonal CVE was 29% (95% CI, 14%-42%), absolute CVE was 39% (95% CI, 6%-60%), relative CVE was 31% (95% CI, 15% to 44%), and relative CVE of second boosters was 34% (95% CI, 18%-47%) against all SARS-CoV-2 variants. In the same interval, seasonal CVE was 44% (95% CI, -10% to 75%), absolute CVE was 52% (95% CI, -23% to 82%), relative CVE was 47% (95% CI, -8% to 77%), and relative CVE of second boosters was 46% (95% CI, -13% to 77%) during a period of high XBB circulation. Estimates decreased with time since vaccination, with no protection from 180 days after vaccination.

Conclusions and Relevance

In this case-control study among older Europeans, all CVE approaches suggested that COVID-19 vaccines administered in autumn and winter 2022 to 2023 offered at least 3 months of protection against symptomatic, medically attended, laboratory-confirmed SARS-CoV-2 infection. The effectiveness of new COVID-19 vaccines against emerging SARS-CoV-2 variants should be continually monitored using CVE seasonal approaches.

COVID-19 Across Pandemic Variant Periods: The Severe Acute Respiratory Infection-Preparedness (SARI-PREP) Study

IMPORTANCE

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has evolved through multiple phases in the United States, with significant differences in patient centered outcomes with improvements in hospital strain, medical countermeasures, and overall understanding of the disease. We describe how patient characteristics changed and care progressed over the various pandemic phases; we also emphasize the need for an ongoing clinical network to improve the understanding of known and novel respiratory viral diseases.

OBJECTIVES

To describe how patient characteristics and care evolved across the various COVID-19 pandemic periods in those hospitalized with viral severe acute respiratory infection (SARI).

DESIGN

Severe Acute Respiratory Infection-Preparedness (SARI-PREP) is a Centers for Disease Control and Prevention Foundation-funded, Society of Critical Care Medicine Discovery-housed, longitudinal multicenter cohort study of viral pneumonia. We defined SARI patients as those hospitalized with laboratory-confirmed respiratory viral infection and an acute syndrome of fever, cough, and radiographic infiltrates or hypoxemia. We collected patient-level data including demographic characteristics, comorbidities, acute physiologic measures, serum and respiratory specimens, therapeutics, and outcomes. Outcomes were described across four pandemic variant periods based on a SARS-CoV-2 sequenced subsample: pre-Delta, Delta, Omicron BA.1, and Omicron post-BA.1.

SETTING

Multicenter cohort of adult patients admitted to an acute care ward or ICU from seven hospitals representing diverse geographic regions across the United States.

PARTICIPANTS

Patients with SARI caused by infection with respiratory viruses.

MAIN OUTCOMES AND RESULTS

Eight hundred seventy-four adult patients with SARI were enrolled at seven study hospitals between March 2020 and April 2023. Most patients (780, 89%) had SARS-CoV-2 infection. Across the COVID-19 cohort, median age was 60 years (interquartile range, 48.0-71.0 yr) and 66% were male. Almost half (430, 49%) of the study population belonged to underserved communities. Most patients (76.5%) were admitted to the ICU, 52.5% received mechanical ventilation, and observed hospital mortality was 25.5%. As the pandemic progressed, we observed decreases in ICU utilization (94% to 58%), hospital length of stay (median, 26.0 to 8.5 d), and hospital mortality (32% to 12%), while the number of comorbid conditions increased.

CONCLUSIONS AND RELEVANCE

We describe increasing comorbidities but improved outcomes across pandemic variant periods, in the setting of multiple factors, including evolving care delivery, countermeasures, and viral variants. An understanding of patient-level factors may inform treatment options for subsequent variants and future novel pathogens.

Comparison of COVID-19 Hospitalization and Death Between Solid Organ Transplant Recipients and the General Population in Canada, 2020-2022

Background

Solid organ transplant recipients have a high risk of severe outcomes from SARS-CoV-2 infection. A comprehensive understanding of the impact of the COVID-19 pandemic across multiple waves in the solid organ transplant population and how this compares to the general population is limited. We conducted a population-based cohort study using linked administrative healthcare databases from Ontario, Canada to answer this question.

Methods

We included 15 306 solid organ transplant recipients and 12 160 904 individuals from the general population. Our primary outcome was the rate (per 100 person-years) of severe COVID-19 (ie, hospitalization or death with a positive SARS-CoV-2 test) occurring between January 25, 2020, and November 30, 2022.

Results

Compared with the general population, solid organ transplant recipients had almost a 6 times higher rate of severe COVID-19 (20.39 versus 3.44 per 100 person-years), with almost 5.5 times as high a rate of death alone (4.19 versus 0.77 per 100 person-years). Transplant recipients with severe COVID-19 were substantially younger (60.1 versus 66.5 y) and had more comorbidities. The rate of severe COVID-19 declined over time in the solid organ transplant population, with an incidence rate of 41.25 per 100 person-years in the first wave (January 25, 2020, to August 31, 2020) and 18.41 in the seventh wave (June 19, 2022, to November 30, 2022, Omicron era).

Conclusions

Solid organ transplant recipients remain at high risk of severe outcomes when they are infected with SARS-CoV-2. Resources and strategies to mitigate the impact of SARS-CoV-2 exposure are needed in this vulnerable patient population.

Deviation from the recommended schedule: optimal dosing interval for a two-dose vaccination programme

Optimizing vaccination impact during an emerging disease becomes crucial when vaccine supply is limited, and robust protection requires multiple doses. Facing this challenge during the early stages of the COVID-19 vaccine deployment, a pivotal policy question arose: whether to administer a single dose to a larger proportion of the population by deferring the second dose, or to prioritize stronger protection for a smaller subset of the population with the established dosing interval from clinical trials. Using a delay-differential model and considering waning immunity and distribution capacity, we compared these strategies. We found that the efficacy of the first dose significantly influences the impact of delaying the second dose. Even for a relatively low efficacy of the first dose, a delayed strategy may outperform vaccination with the recommended dosing interval in reducing short-term hospitalizations and deaths despite increase in infections. The optimal delay, however, depends on the specific outcome measured and timelines within which the vaccination strategy is evaluated. We found transition lines for the relative reduction of infection, hospitalization and death below which vaccination with the recommended schedule is the preferred strategy. In a realistic parameter space, our results highlight scenarios in which the conclusions of previous studies are invalid.

Differences in virus and immune dynamics for SARS-CoV-2 Delta and Omicron infections by age and vaccination histories

Vaccination against COVID-19 was integral to controlling the pandemic that persisted with the continuous emergence of SARS-CoV-2 variants. Using a mathematical model describing SARS-CoV-2 within-host infection dynamics, we estimate differences in virus and immunity due to factors of infecting variant, age, and vaccination history (vaccination brand, number of doses and time since vaccination). We fit our model in a Bayesian framework to upper respiratory tract viral load measurements obtained from cases of Delta and Omicron infections in Singapore, of whom the majority only had one nasopharyngeal swab measurement. With this dataset, we are able to recreate similar trends in URT virus dynamics observed in past within-host modelling studies fitted to longitudinal patient data.We found that Omicron had higher R0,within values than Delta, indicating greater initial cell-to-cell spread of infection within the host. Moreover, heterogeneities in infection dynamics across patient subgroups could be recreated by fitting immunity-related parameters as vaccination history-specific, with or without age modification. Our model results are consistent with the notion of immunosenescence in SARS-CoV-2 infection in elderly individuals, and the issue of waning immunity with increased time since last vaccination. Lastly, vaccination was not found to subdue virus dynamics in Omicron infections as well as it had for Delta infections.This study provides insight into the influence of vaccine-elicited immunity on SARS-CoV-2 within-host dynamics, and the interplay between age and vaccination history. Furthermore, it demonstrates the need to disentangle host factors and changes in pathogen to discern factors influencing virus dynamics. Finally, this work demonstrates a way forward in the study of within-host virus dynamics, by use of viral load datasets including a large number of patients without repeated measurements.

Hybrid immunity from severe acute respiratory syndrome coronavirus 2 infection and vaccination in Canadian adults: A cohort study

Background

Few national-level studies have evaluated the impact of 'hybrid' immunity (vaccination coupled with recovery from infection) from the Omicron variants of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

Methods

From May 2020 to December 2022, we conducted serial assessments (each of ~4000-9000 adults) examining SARS-CoV-2 antibodies within a mostly representative Canadian cohort drawn from a national online polling platform. Adults, most of whom were vaccinated, reported viral test-confirmed infections and mailed self-collected dried blood spots (DBSs) to a central lab. Samples underwent highly sensitive and specific antibody assays to spike and nucleocapsid protein antigens, the latter triggered only by infection. We estimated cumulative SARS-CoV-2 incidence prior to the Omicron period and during the BA.1/1.1 and BA.2/5 waves. We assessed changes in antibody levels and in age-specific active immunity levels.

Results

Spike levels were higher in infected than in uninfected adults, regardless of vaccination doses. Among adults vaccinated at least thrice and infected more than 6 months earlier, spike levels fell notably and continuously for the 9-month post-vaccination. In contrast, among adults infected within 6 months, spike levels declined gradually. Declines were similar by sex, age group, and ethnicity. Recent vaccination attenuated declines in spike levels from older infections. In a convenience sample, spike antibody and cellular responses were correlated. Near the end of 2022, about 35% of adults above age 60 had their last vaccine dose more than 6 months ago, and about 25% remained uninfected. The cumulative incidence of SARS-CoV-2 infection rose from 13% (95% confidence interval 11-14%) before omicron to 78% (76-80%) by December 2022, equating to 25 million infected adults cumulatively. However, the coronavirus disease 2019 (COVID-19) weekly death rate during the BA.2/5 waves was less than half of that during the BA.1/1.1 wave, implying a protective role for hybrid immunity.

Conclusions

Strategies to maintain population-level hybrid immunity require up-to-date vaccination coverage, including among those recovering from infection. Population-based, self-collected DBSs are a practicable biological surveillance platform.

Funding

Funding was provided by the COVID-19 Immunity Task Force, Canadian Institutes of Health Research, Pfizer Global Medical Grants, and St. Michael's Hospital Foundation. PJ and ACG are funded by the Canada Research Chairs Program.

COVID-19 Booster Vaccination Status and Long COVID in the United States: A Nationally Representative Cross-Sectional Study

Early studies have found that the initial COVID-19 vaccination series was protective against severe symptoms and long COVID. However, few studies have explored the association of booster doses on severe disease outcomes and long COVID. This cross-sectional analysis used data from the 2022 US National Health Interview Survey data to investigate how vaccination status correlates with COVID-19 infection severity and long COVID among previously infected individuals. Participants were categorized into three groups: those who had received at least one booster, those with only the initial complete vaccination series, and those with either an incomplete series or no vaccinations. Out of 9521 survey respondents who reported a past positive COVID-19 test, 51.2% experienced moderate/severe infections, and 17.6% experienced long COVID. Multivariable regression models revealed that receiving at least one booster shot was associated with lower odds of experiencing moderate/severe symptoms (aOR = 0.78, p < 0.001) compared to those unvaccinated or with an incomplete series. Additionally, having at least one booster reduced long COVID odds by 24% (aOR = 0.76, p = 0.003). Completing only the primary vaccine series did not significantly decrease the likelihood of severe illness or long COVID. These findings support the continued promotion of booster vaccinations to mitigate long COVID risks in vulnerable populations.

Protective effectiveness of previous infection against subsequent SARS-Cov-2 infection: systematic review and meta-analysis

Background

The protective effectiveness provided by naturally acquired immunity against SARS-CoV-2 reinfection remain controversial.

Objective

To systematically evaluate the protective effect of natural immunity against subsequent SARS-CoV-2 infection with different variants.

Methods

We searched for related studies published in seven databases before March 5, 2023. Eligible studies included in the analysis reported the risk of subsequent infection for groups with or without a prior SARS-CoV-2 infection. The primary outcome was the overall pooled incidence rate ratio (IRR) of SARS-CoV-2 reinfection/infection between the two groups. We also focused on the protective effectiveness of natural immunity against reinfection/infection with different SARS-CoV-2 variants. We used a random-effects model to pool the data, and obtained the bias-adjusted results using the trim-and-fill method. Meta-regression and subgroup analyses were conducted to explore the sources of heterogeneity. Sensitivity analysis was performed by excluding included studies one by one to evaluate the stability of the results.

Results

We identified 40 eligible articles including more than 20 million individuals without the history of SARS-CoV-2 vaccination. The bias-adjusted efficacy of naturally acquired antibodies against reinfection was estimated at 65% (pooled IRR = 0.35, 95% CI = 0.26-0.47), with higher efficacy against symptomatic COVID-19 cases (pooled IRR = 0.15, 95% CI = 0.08-0.26) than asymptomatic infection (pooled IRR = 0.40, 95% CI = 0.29-0.54). Meta-regression revealed that SARS-CoV-2 variant was a statistically significant effect modifier, which explaining 46.40% of the variation in IRRs. For different SARS-CoV-2 variant, the pooled IRRs for the Alpha (pooled IRR = 0.11, 95% CI = 0.06-0.19), Delta (pooled IRR = 0.19, 95% CI = 0.15-0.24) and Omicron (pooled IRR = 0.61, 95% CI = 0.42-0.87) variant were higher and higher. In other subgroup analyses, the pooled IRRs of SARS-CoV-2 infection were statistically various in different countries, publication year and the inclusion end time of population, with a significant difference (p = 0.02, p < 0.010 and p < 0.010), respectively. The risk of subsequent infection in the seropositive population appeared to increase slowly over time. Despite the heterogeneity in included studies, sensitivity analyses showed stable results.

Conclusion

Previous SARS-CoV-2 infection provides protection against pre-omicron reinfection, but less against omicron. Ongoing viral mutation requires attention and prevention strategies, such as vaccine catch-up, in conjunction with multiple factors.

SARS-CoV-2 breakthrough infections enhance T cell response magnitude, breadth, and epitope repertoire

Little is known about the effect of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 or SARS2) vaccine breakthrough infections (BTIs) on the magnitude and breadth of the T cell repertoire after exposure to different variants. We studied samples from individuals who experienced symptomatic BTIs during Delta or Omicron waves. In the pre-BTI samples, 30% of the donors exhibited substantial immune memory against non-S (spike) SARS2 antigens, consistent with previous undiagnosed asymptomatic SARS2 infections. Following symptomatic BTI, we observed (1) enhanced S-specific CD4 and CD8 T cell responses in donors without previous asymptomatic infection, (2) expansion of CD4 and CD8 T cell responses to non-S targets (M, N, and nsps) independent of SARS2 variant, and (3) generation of novel epitopes recognizing variant-specific mutations. These variant-specific T cell responses accounted for 9%-15% of the total epitope repertoire. Overall, BTIs boost vaccine-induced immune responses by increasing the magnitude and by broadening the repertoire of T cell antigens and epitopes recognized.

Evaluating the impact of extended dosing intervals on mRNA COVID-19 vaccine effectiveness in adolescents

Extending the dosing interval of a primary series of mRNA COVID-19 vaccination has been employed to reduce myocarditis risk in adolescents, but previous evaluation of impact on vaccine effectiveness (VE) is limited to risk after second dose. Here, we quantified the impact of the dosing interval based on case notifications and vaccination uptake in Hong Kong from January to April 2022. We estimated that the hazard ratio (HR) and odds ratio (OR) of infections after the second dose for extended (28 days or more) versus regular (21-27 days) dosing intervals ranged from 0.86 to 0.99 from calendar-time proportional hazards models, and from 0.85 to 0.87 from matching approaches, respectively. Adolescents in the extended dosing groups (including those who did not receive a second dose in the study period) had a higher hazard of infection than those with a regular dosing interval during the intra-dose period (HR: 1.66; 95% CI: 1.07, 2.59; p = 0.02) after the first dose. Implementing an extended dosing interval should consider multiple factors including the degree of myocarditis risk, the degree of protection afforded by each dose, and the extra protection achievable using an extended dosing interval.

sTREM-1 as a Predictive Biomarker for Disease Severity and Prognosis in COVID-19 Patients

Background

Research on biomarkers associated with the severity and adverse prognosis of COVID-19 can be beneficial for improving patient outcomes. However, there is limited research on the role of soluble TREM-1 (sTREM-1) in predicting the severity and prognosis of COVID-19 patients.

Methods

A total of 115 COVID-19 patients admitted to the emergency department of Beijing Youan Hospital from February to May 2023 were included in the study. Demographic information, laboratory measurements, and blood samples for sTREM-1 levels were collected upon admission.

Results

Our study found that sTREM-1 levels in the plasma of COVID-19 patients increased with the severity of the disease (moderate vs mild, p=0.0013; severe vs moderate, p=0.0195). sTREM-1 had good predictive value for disease severity and 28-day mortality (area under the ROC curve was 0.762 and 0.805, respectively). sTREM-1 also exhibited significant correlations with age, body temperature, respiratory rate, PaO2/FiO2, PCT, CRP, and CAR. Ultimately, through multivariate logistic regression analysis, we determined that sTREM-1 (OR 1.008, 95% CI: 1.002-1.013, p=0.005), HGB (OR 0.966, 95% CI: 0.935-0.998, p=0.036), D-dimer (OR 1.001, 95% CI: 1.000-1.001, p=0.009), and CAR (OR 1.761, 95% CI: 1.154-2.688, p=0.009) were independent predictors of 28-day mortality in COVID-19 patients. The combination of these four markers yielded a strong predictive value for 28-day mortality in COVID-19 cases with an AUC of 0.919 (95% CI: 0.857 -0.981).

Conclusion

sTREM-1 demonstrated good predictive value for disease severity and 28-day mortality, serving as an independent prognostic factor for adverse patient outcomes. In the future, we anticipate conducting large-scale multicenter studies to validate our research findings.

Epidemiology, risk factors, and vaccine effectiveness for SARS-CoV-2 infection among healthcare workers during the omicron pandemic in Shanghai, China

Background

The COVID-19 pandemic has exposed healthcare workers (HCWs) to serious risk of infection. The aims of our study were to investigate the epidemiological characteristics and risk factors of SARS-CoV-2 infection among HCWs, and evaluate the vaccine effectiveness (VE) during the Omicron pandemic in Shanghai, China.

Methods

Active surveillance of COVID-19 was performed among HCWs who worked in Shanghai General Hospital from December 2022 to January 2023. A case-control study was conducted by questionnaire survey to analyse the infection-related risk factors. A retrospective cohort study was explored to evaluate VE against primary infection.

Results

During the Omicron outbreak, 2,008 of 2,460 (81.6%) HCWs were infected with SARS-CoV-2. The infection rate was higher in women, younger age groups, nurses and medical technicians. Among the 1,742 participants in the questionnaire, 1,463 (84.0%) were tested positive, and 95.1% of them developed symptoms. Most of the infections (53.0%) were acquired outside the hospital. The risk factors associated with higher odds of infection were working in the emergency department (aOR 3.77, 95% CI 1.69-8.38) and medical examination area (aOR 2.47, 95% CI 1.10-5.51). The protective factors associated with lower odds of infection were previous infection with SARS-CoV-2 (aOR 0.01, 95% CI 0-0.07) and receiving four doses of vaccines (aOR 0.40, 95% CI 0.17-0.97). For frontline HCWs, those who had oral-nasal exposure to coworkers were more likely to be infected (aOR 1.74, 95% CI 1.21-2.51). In VE analysis, the risk of primary infection was lower in HCWs who received the emergency heterologous booster (the fourth dose) during the epidemic (aHR 0.25, 95% CI 0.15-0.40), resulting in an adjusted-VE of 75.1%.

Conclusions

In response to future pandemic, it is important for public health policies to aim at protecting HCWs through risk-differentiated infection control measures, strengthening personal protection and recommending vaccination to vulnerable individuals before the arrival of Omicron wave.

Uptake, effectiveness and safety of COVID-19 vaccines in individuals at clinical risk due to immunosuppressive drug therapy or transplantation procedures: a population-based cohort study in England

BACKGROUND

Immunocompromised individuals are at increased risk of severe COVID-19 outcomes, underscoring the importance of COVID-19 vaccination in this population. The lack of comprehensive real-world data on vaccine uptake, effectiveness and safety in these individuals presents a critical knowledge gap, highlighting the urgency to better understand and address the unique challenges faced by immunocompromised individuals in the context of COVID-19 vaccination.

METHODS

We analysed data from 12,274,946 people in the UK aged > 12 years from 01/12/2020 to 11/04/2022. Of these, 583,541 (4.8%) were immunocompromised due to immunosuppressive drugs, organ transplants, dialysis or chemotherapy. We undertook a cohort analysis to determine COVID-19 vaccine uptake, nested case-control analyses adjusted for comorbidities and sociodemographic characteristics to determine effectiveness of vaccination against COVID-19 hospitalisation, ICU admission and death, and a self-controlled case series assessing vaccine safety for pre-specified adverse events of interest.

RESULTS

Overall, 93.7% of immunocompromised individuals received at least one COVID-19 vaccine dose, with 80.4% having received three or more doses. Uptake reduced with increasing deprivation (hazard ratio [HR] 0.78 [95%CI 0.77-0.79] in the most deprived quintile compared to the least deprived quintile for the first dose). Estimated vaccine effectiveness against COVID-19 hospitalisation 2-6 weeks after the second and third doses compared to unvaccinated was 78% (95%CI 72-83) and 91% (95%CI 88-93) in the immunocompromised population, versus 85% (95%CI 83-86) and 86% (95%CI 85-89), respectively, for the general population. Results showed COVID-19 vaccines were protective against intensive care unit (ICU) admission and death in both populations, with effectiveness of over 92% against COVID-19-related death and up to 95% in reducing ICU admissions for both populations following the third dose. COVID-19 vaccines were generally safe for immunocompromised individuals, though specific doses of ChAdOx1, mRNA-1273 and BNT162b2 raised risks of specific cardiovascular/neurological conditions.

CONCLUSIONS

COVID-19 vaccine uptake is high in immunocompromised individuals on immunosuppressive drug therapy or who have undergone transplantation procedures, with documented disparities by deprivation. Findings suggest that COVID-19 vaccines are protective against severe COVID-19 outcomes in this vulnerable population, and show a similar safety profile in immunocompromised individuals and the general population, despite some increased risk of adverse events. These results underscore the importance of ongoing vaccination prioritisation for this clinically at-risk population to maximise protection against severe COVID-19 outcomes.

Cost-effectiveness of severe acute respiratory coronavirus virus 2 (SARS-CoV-2) testing and isolation strategies in nursing homes

OBJECTIVE

Nursing home residents may be particularly vulnerable to coronavirus disease 2019 (COVID-19). Therefore, a question is when and how often nursing homes should test staff for COVID-19 and how this may change as severe acute respiratory coronavirus virus 2 (SARS-CoV-2) evolves.

DESIGN

We developed an agent-based model representing a typical nursing home, COVID-19 spread, and its health and economic outcomes to determine the clinical and economic value of various screening and isolation strategies and how it may change under various circumstances.

RESULTS

Under winter 2023-2024 SARS-CoV-2 omicron variant conditions, symptom-based antigen testing averted 4.5 COVID-19 cases compared to no testing, saving $191 in direct medical costs. Testing implementation costs far outweighed these savings, resulting in net costs of $990 from the Centers for Medicare & Medicaid Services perspective, $1,545 from the third-party payer perspective, and $57,155 from the societal perspective. Testing did not return sufficient positive health effects to make it cost-effective [$50,000 per quality-adjusted life-year (QALY) threshold], but it exceeded this threshold in ≥59% of simulation trials. Testing remained cost-ineffective when routinely testing staff and varying face mask compliance, vaccine efficacy, and booster coverage. However, all antigen testing strategies became cost-effective (≤$31,906 per QALY) or cost saving (saving ≤$18,372) when the severe outcome risk was ≥3 times higher than that of current omicron variants.

CONCLUSIONS

SARS-CoV-2 testing costs outweighed benefits under winter 2023-2024 conditions; however, testing became cost-effective with increasingly severe clinical outcomes. Cost-effectiveness can change as the epidemic evolves because it depends on clinical severity and other intervention use. Thus, nursing home administrators and policy makers should monitor and evaluate viral virulence and other interventions over time.

Assessing the dynamics and impact of COVID-19 vaccination on disease spread: A data-driven approach

The COVID-19 pandemic has significantly impacted global health, social, and economic situations since its emergence in December 2019. The primary focus of this study is to propose a distinct vaccination policy and assess its impact on controlling COVID-19 transmission in Malaysia using a Bayesian data-driven approach, concentrating on the year 2021. We employ a compartmental Susceptible-Exposed-Infected-Recovered-Vaccinated (SEIRV) model, incorporating a time-varying transmission rate and a data-driven method for its estimation through an Exploratory Data Analysis (EDA) approach. While no vaccine guarantees total immunity against the disease, and vaccine immunity wanes over time, it is critical to include and accurately estimate vaccine efficacy, as well as a constant vaccine immunity decay or wane factor, to better simulate the dynamics of vaccine-induced protection over time. Based on the distribution and effectiveness of vaccines, we integrated a data-driven estimation of vaccine efficacy, calculated at 75% for Malaysia, underscoring the model's realism and relevance to the specific context of the country. The Bayesian inference framework is used to assimilate various data sources and account for underlying uncertainties in model parameters. The model is fitted to real-world data from Malaysia to analyze disease spread trends and evaluate the effectiveness of our proposed vaccination policy. Our findings reveal that this distinct vaccination policy, which emphasizes an accelerated vaccination rate during the initial stages of the program, is highly effective in mitigating the spread of COVID-19 and substantially reducing the pandemic peak and new infections. The study found that vaccinating 57-66% of the population (as opposed to 76% in the real data) with a better vaccination policy such as proposed here is able to significantly reduce the number of new infections and ultimately reduce the costs associated with new infections. The study contributes to the development of a robust and informative representation of COVID-19 transmission and vaccination, offering valuable insights for policymakers on the potential benefits and limitations of different vaccination policies, particularly highlighting the importance of a well-planned and efficient vaccination rollout strategy. While the methodology used in this study is specifically applied to national data from Malaysia, its successful application to local regions within Malaysia, such as Selangor and Johor, indicates its adaptability and potential for broader application. This demonstrates the model's adaptability for policy assessment and improvement across various demographic and epidemiological landscapes, implying its usefulness for similar datasets from various geographical regions.

Estimates of SARS-CoV-2 Hospitalization and Fatality Rates in the Prevaccination Period, United States

Few precise estimates of hospitalization and fatality rates from COVID-19 exist for naive populations, especially within demographic subgroups. We estimated rates among persons with SARS-CoV-2 infection in the United States during May 1-December 1, 2020, before vaccines became available. Both rates generally increased with age; fatality rates were highest for persons >85 years of age (24%) and lowest for children 1-14 years of age (0.01%). Age-adjusted case hospitalization rates were highest for African American or Black, not Hispanic persons (14%), and case-fatality rates were highest for Asian or Pacific Islander, not Hispanic persons (4.4%). Eighteen percent of hospitalized patients and 44.2% of those admitted to an intensive care unit died. Male patients had higher hospitalization (6.2% vs. 5.2%) and fatality rates (1.9% vs. 1.5%) than female patients. These findings highlight the importance of collecting surveillance data to devise appropriate control measures for persons in underserved racial/ethnic groups and older adults.