Trends in Laboratory-Confirmed SARS-CoV-2 Reinfections and Associated Hospitalizations and Deaths Among Adults Aged ≥18 Years - 18 U.S. Jurisdictions, September 2021-December 2022

Stuck in pandemic uncertainty: a review of the persistent effects of COVID-19 infection in immune-deficient people

BACKGROUND

People who are immune-deficient/disordered (IDP) are underrepresented in COVID-19 studies. Specifically, there is limited research on post-SARS-CoV-2 infection outcomes, including viral persistence and long-term sequelae in these populations.

OBJECTIVES

This review aimed to examine the published literature on the occurrence of persistent SARS-CoV-2 positivity, relapse, reinfections, variant coinfection, and post-acute sequelae of COVID-19 in IDP. Although the available literature largely centred on those with secondary immunodeficiencies, studies on people with inborn errors of immunity are also included.

SOURCES

PubMed was searched using medical subject headings terms to identify relevant articles from the last 4 years. Articles on primary and secondary immunodeficiencies were chosen, and a special emphasis was placed on including articles that studied people with inborn errors of immunity. The absence of extensive cohort studies including these individuals has limited most articles in this review to case reports, whereas the articles focusing on secondary immunodeficiencies include larger cohort, case-control, and cross-sectional studies. Articles focusing solely on HIV/AIDS were excluded.

CONTENT

Scientific literature suggests that IDP of any age are more likely to experience persistent SARS-CoV-2 infections. Although adult IDP exhibits a higher rate of post-acute sequelae of COVID-19, milder COVID-19 infections in children may reduce their risk of experiencing post-acute sequelae of COVID-19. Reinfections and coinfections may occur at a slightly higher rate in IDP than in the general population.

IMPLICATIONS

Although IDP experience increased viral persistence and inter-host evolution, it is unlikely that enough evidence can be generated at the population-level to support or refute the hypothesis that infections in IDP are significantly more likely to result in variants of concern than infections in the general population. Additional research on the relationship between viral persistence and the rate of long-term sequelae in IDP could inform the understanding of the immune response to SARS-CoV-2 in IDP and the general population.

Hybrid Immunity and SARS-CoV-2 Antibodies: Results of the HEROES-RECOVER Prospective Cohort Study

BACKGROUND

There are limited data on whether hybrid immunity differs by count and order of immunity-conferring events (infection with severe acute respiratory syndrome coronavirus 2 [SARS-CoV-2] or vaccination against coronavirus disease 2019 [COVID-19]). From a multi-site cohort of frontline workers, we examined the heterogeneity of the effect of hybrid immunity on SARS-CoV-2 antibody levels.

METHODS

Exposures included event count and event order, categorized into 7 permutations. Outcome was level of serum antibodies against receptor-binding domain (RBD) of the ancestral SARS-CoV-2 spike protein (total RBD-binding immunoglobulin). Means were examined up to 365 days after each of the first to seventh events.

RESULTS

Analysis included 5793 participants measured from 7 August 2020 to 15 April 2023. Hybrid immunity from infection before 1 or 2 vaccine doses elicited modestly superior antibody responses after the second and third events (compared with infections or vaccine doses alone). This superiority was not repeated after additional events. Among adults infected before vaccination, adjusted geometric mean ratios (95% confidence interval [CI]) of anti-RBD early response (versus vaccinated only) were 1.23 (1.14-1.33), 1.09 (1.03-1.14), 0.87 (.81-.94), and 0.99 (.85-1.15) after the second to fifth events, respectively. Post-vaccination infections elicited superior responses; adjusted geometric mean ratios (95% CI) of anti-RBD early response (versus vaccinated only) were 0.93 (.75-1.17), 1.11 (1.06-1.16), 1.17 (1.11-1.24), and 1.20 (1.07-1.34) after the second to fifth events, respectively.

CONCLUSIONS

Evidence of heterogeneity in antibody levels by permutations of infection and vaccination history could inform COVID-19 vaccination policy.

Insights from an N3C RECOVER EHR-based cohort study characterizing SARS-CoV-2 reinfections and Long COVID

BACKGROUND

Although the COVID-19 pandemic has persisted for over 3 years, reinfections with SARS-CoV-2 are not well understood. We aim to characterize reinfection, understand development of Long COVID after reinfection, and compare severity of reinfection with initial infection.

METHODS

We use an electronic health record study cohort of over 3 million patients from the National COVID Cohort Collaborative as part of the NIH Researching COVID to Enhance Recovery Initiative. We calculate summary statistics, effect sizes, and Kaplan-Meier curves to better understand COVID-19 reinfections.

RESULTS

Here we validate previous findings of reinfection incidence (6.9%), the occurrence of most reinfections during the Omicron epoch, and evidence of multiple reinfections. We present findings that the proportion of Long COVID diagnoses is higher following initial infection than reinfection for infections in the same epoch. We report lower albumin levels leading up to reinfection and a statistically significant association of severity between initial infection and reinfection (chi-squared value: 25,697, p-value: <0.0001) with a medium effect size (Cramer's V: 0.20, DoF = 3). Individuals who experienced severe initial and first reinfection were older in age and at a higher mortality risk than those who had mild initial infection and reinfection.

CONCLUSIONS

In a large patient cohort, we find that the severity of reinfection appears to be associated with the severity of initial infection and that Long COVID diagnoses appear to occur more often following initial infection than reinfection in the same epoch. Future research may build on these findings to better understand COVID-19 reinfections.

COVID-19 Infection in Ultramarathon Runners: Findings of the Ultrarunners Longitudinal TRAcking Study

OBJECTIVE

Ultramarathon runners are a unique patient population who have been shown to have a lower rate of severe chronic medical conditions. This study aimed to determine the effect that COVID-19 infection has had on this population and their running behavior.

DESIGN

The Ultrarunners Longitudinal TRAcking (ULTRA) Study is a large longitudinal study of ultramarathon runners. Questions on health status, running behavior, and COVID-19 infection were included in the most recent survey.

SETTING

Community survey.

PARTICIPANTS

Seven hundred thirty-four ultramarathon runners participated in the study.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Personal, exercise, and COVID-19 infection history.

RESULTS

52.7% of study participants reported having been symptomatic from a COVID-19 infection, with 6.7% testing positive multiple times. Participants required a total of 4 days of hospitalization. The most common symptoms included fever (73.6%), fatigue (68.5%), sore throat (68.2%), runny nose (67.7%), and cough (67.4%). Cardiovascular symptoms, which are of particular interest in the running population, included shortness of breath (46.3%), tachycardia (44.7%), chest pain (36.2%), and wheezing (33.3%). A total of 50 subjects (6.8%) reported long COVID (symptoms lasting more than 12 weeks).

CONCLUSIONS

Severe COVID-19 infection has been rare in this population of ultramarathon runners, although symptomatic infection that affects running is common. To support the well-being of this group of highly active athletes, clinicians should appreciate that cardiovascular symptoms are common and the long-term significance of these symptoms in runners is unknown.

LEVEL OF EVIDENCE

Level 2 prospective study.

Relationship between acute SARS-CoV-2 viral clearance with Long COVID Symptoms: a cohort study

Introduction

The relationship between SARS-CoV-2 viral dynamics during acute infection and the development of long COVID is largely unknown.

Methods

A total of 7361 asymptomatic community-dwelling people enrolled in the Test Us at Home parent study between October 2021 and February 2022. Participants self-collected anterior nasal swabs for SARS-CoV-2 RT-PCR testing every 24-48 hours for 10-14 days, regardless of symptom or infection status. Participants who had no history of COVID-19 at enrollment and who were subsequently found to have ≥1 positive SARS-CoV-2 RT-PCR test during the parent study were recontacted in August 2023 and asked whether they had experienced long COVID, defined as the development of new symptoms lasting 3 months or longer following SARS-CoV-2 infection. Participant's cycle threshold values were converted into viral loads, and slopes of viral clearance were modeled using post-nadir viral loads. Using a log binomial model with the modeled slopes as the exposure, we calculated the relative risk of subsequently developing long COVID with 1-2 symptoms, 3-4 symptoms, or 5+ symptoms, adjusting for age, number of symptoms, and SARS-CoV-2 variant. Adjusted relative risk (aRR) of individual long COVID symptoms based on viral clearance was also calculated.

Results

172 participants were eligible for analyses, and 59 (34.3%) reported experiencing long COVID. The risk of long COVID with 3-4 symptoms and 5+ symptoms increased by 2.44 times (aRR: 2.44; 95% CI: 0.88-6.82) and 4.97 times (aRR: 4.97; 95% CI: 1.90-13.0) per viral load slope-unit increase, respectively. Participants who developed long COVID had significantly longer times from peak viral load to viral clearance during acute disease than those who never developed long COVID (8.65 [95% CI: 8.28-9.01] vs. 10.0 [95% CI: 9.25-10.8]). The slope of viral clearance was significantly positively associated with long COVID symptoms of fatigue (aRR: 2.86; 95% CI: 1.22-6.69), brain fog (aRR: 4.94; 95% CI: 2.21-11.0), shortness of breath (aRR: 5.05; 95% CI: 1.24-20.6), and gastrointestinal symptoms (aRR: 5.46; 95% CI: 1.54-19.3).

Discussion

We observed that longer time from peak viral load to viral RNA clearance during acute COVID-19 was associated with an increased risk of developing long COVID. Further, slower clearance rates were associated with greater number of symptoms of long COVID. These findings suggest that early viral-host dynamics are mechanistically important in the subsequent development of long COVID.

Recent symptomatic Omicron infection reduced COVID-19 pneumonia risk during reinfection: A computed tomography-based cohort study

OBJECTIVES

SARS-CoV-2 infection could cause persistent lung injury or indicate potential genetic susceptibilities. Although infection-elicited hybrid immunity could protect against severe COVID-19, it remains unknown whether recent infection could reduce pneumonia risk during reinfection due to insufficient viral and chest computed tomography (CT) screening.

METHODS

A total of 15,598 patients, 96% fully vaccinated and 52% boosted, from Xiangyang, China, who had symptomatic COVID-19 and chest CT scans during the first Omicron BF.7 wave in December 2022 to January 2023, were followed through the second Omicron XBB.1.5 wave between May and August 2023. A total of 17,968 second-wave patients with COVID-19 with chest CT scans but without previous symptomatic COVID-19 were enrolled as first-time infection controls.

RESULTS

A total of 19.6% (3,061 of 15,598) first-wave patients were diagnosed with pneumonia. Among second-wave reinfected patients, only 0.2% (four of 2202) developed pneumonia, which was lower than the 1.7% (311 of 17,968) pneumonia prevalence among the second-wave first-time patients, with an adjusted relative risk of 0.11 (95% confidence interval: 0.04-0.29). A total of 1.3% (40 of 3,039) first-wave pneumonia survivors showed residual abnormal patterns in follow-up CT scans within 8 months after pneumonia diagnosis.

CONCLUSIONS

In a highly vaccinated population, previous symptomatic Omicron infection within 8 months reduced pneumonia risk during reinfection. Uninfected individuals might need up-to-date vaccination to reduce pneumonia risk.

COVID-19 vaccination, infection, and symptoms among cancer survivors in the United States

The experiences of cancer survivors with the COVID-19 pandemic in the United States during 2021 and 2022, when vaccinations became widely available, are largely undocumented. Using nationally representative survey data in 2021 and 2022, we found that compared with adults without a cancer history, cancer survivors were more likely to have at least 2 COVID-19 vaccines (2021: 66.6% vs 62.3%, P = .003; 2022: 77.0% vs 72.4%, P < .001) and as likely to have a COVID-19 infection history (2021: 14.1% vs 14.2%, P = .93; 2022: 39.9% vs 39.3%, P = .55) but, once infected, were more likely to develop moderate to severe symptoms (2021: 62.5% vs 54.2%, P = .02; 54.5% vs 61.3%; P = .13). Among cancer survivors, younger age, lower educational attainment, lack of health insurance, and more comorbidities were statistically significantly associated with lower vaccination rates (P < .001). Among infected cancer survivors, being female and younger were associated with higher likelihood of developing moderate to severe symptoms (P < .001). Our findings suggest tailored efforts to prevent and control COVID-19 infections for cancer survivors.

Dissecting the dynamics of SARS-CoV-2 reinfections in blood donors with pauci- or asymptomatic COVID-19 disease course at initial infection

BACKGROUND

Understanding the dynamics of SARS-CoV-2 reinfections is crucial for public health policy, vaccine development, and long-term disease management. However, data on reinfections in the general population remains scarce.

OBJECTIVES

This study aimed to investigate SARS-CoV-2 antibody dynamics among Austrian blood donors, representing healthy adults, over two years following primary infection and to evaluate the reinfection risk.

METHODS

117,895 blood donations were analysed for SARS-CoV-2 total anti-N levels from June 2020 to December 2023. We examined anti-N and anti-S antibody dynamics and in vitro functionality in 230 study participants at five defined times during 24 months, assessing associations with demographics, vaccination status, and reinfection awareness.

RESULTS

The seroprevalence of SARS-CoV-2 infection-derived anti-N antibodies increased over time, reaching 90% by February 2023 and remaining at that level since then. According to serological screenings, we found an 88% reinfection rate, which is in contrast to participants' reports indicating a reinfection rate of 59%. Our data further reveal that about 26% of reinfections went completely unnoticed. Antibody dynamics were independent of age, sex, and ABO blood group. Interestingly, individuals with multiple reinfections reported symptoms more frequently during their primary infection. Our results further show that vaccination modestly affected reinfection risk and disease course.

CONCLUSION

SARS-CoV-2 reinfections were uncommon until the end of 2021 but became common with the advent of Omicron. This study highlights the underestimation of reinfection rates in healthy adults and underscores the need for continued surveillance, which is an important support for public health policies and intervention strategies.

Development of a colloidal gold-based immunochromatographic assay for rapid detection of nasal mucosal secretory IgA against SARS-CoV-2

Introduction

Infection with SARS-CoV-2 begins in the upper respiratory tract and can trigger the production of mucosal spike-specific secretory IgA (sIgA), which provides protection against reinfection. It has been recognized that individuals with high level of nasal spike-specific IgA have a lower risk of reinfection. However, mucosal spike-specific sIgA wanes over time, and different individuals may have various level of spike-specific sIgA and descending kinetics, leading to individual differences in susceptibility to reinfection. A method for detecting spike-specific sIgA in the nasal passage would be valuable for predicting the risk of reinfection so that people at risk can have better preparedness.

Methods

In this study, we describe the development of a colloidal gold-based immunochromatographic (ICT) strip for detecting SARS-CoV-2 Omicron spike-specific sIgA in nasal mucosal lining fluids (NMLFs).

Results

The ICT strip was designed to detect 0.125 μg or more spike-specific sIgA in 80 μL of NMLFs collected using a nasal swab. Purified nasal sIgA samples from individuals who recently recovered from an Omicron BA.5 infection were used to demonstrate that this ICT strip can specifically detect spike-specific sIgA. The signal levels positively correlated with neutralizing activities against XBB. Subsequent analysis revealed that people with low or undetectable levels of spike-specific sIgA in the nasal passage were more susceptible to SARS-CoV-2 reinfection.

Conclusions

This nasal spike-specific sIgA ICT strip provides a non-invasive, rapid, and convenient method to assess the risk of reinfection for achieving precision preparedness.

Long-term monitoring of SARS-CoV-2 seroprevalence and variants in Ethiopia provides prediction for immunity and cross-immunity

Under-reporting of COVID-19 and the limited information about circulating SARS-CoV-2 variants remain major challenges for many African countries. We analyzed SARS-CoV-2 infection dynamics in Addis Ababa and Jimma, Ethiopia, focusing on reinfection, immunity, and vaccination effects. We conducted an antibody serology study spanning August 2020 to July 2022 with five rounds of data collection across a population of 4723, sequenced PCR-test positive samples, used available test positivity rates, and constructed two mathematical models integrating this data. A multivariant model explores variant dynamics identifying wildtype, alpha, delta, and omicron BA.4/5 as key variants in the study population, and cross-immunity between variants, revealing risk reductions between 24% and 69%. An antibody-level model predicts slow decay leading to sustained high antibody levels. Retrospectively, increased early vaccination might have substantially reduced infections during the delta and omicron waves in the considered group of individuals, though further vaccination now seems less impactful.

A mini review of reinfection with the SARS-CoV-2 Omicron variant

Background

COVID-19 has caused severe morbidity and mortality worldwide. After the end of the dynamic zero-COVID policy in China in December, 2022, concerns regarding reinfection were raised while little was known due to the lack of surveillance data in this country.

Aims

This study reviews the probability, risk factors, and severity of severe acute respiratory syndrome coronavirus 2 Omicron variant reinfection, as well as the interval between infections, risk of onward transmission by reinfected cases, and the role of booster vaccination against reinfection.

Sources

References for this review were identified through searches of PubMed and Web of Science up to September 24, 2023.

Results

The rate of reinfection ranges from 3.1% to 13.0%. Factors associated with a higher risk of reinfection include being female, having comorbidities, and being unvaccinated. Reinfection with the BA.4 or BA.5 variant occurs approximately 180 days after the initial infection. Reinfections are less clinically severe than primary infections, and there is evidence of lower transmissibility. The debate surrounding the effectiveness and feasibility of booster vaccinations in preventing reinfection continues.

Conclusions

The reinfection rate during the Omicron epidemic is significantly higher than in previous epidemic periods. However, the symptoms and infectivity of reinfection were weaker than those of the prior infection. Medical staff and individuals at high risk of reinfection should be vigilant. The efficacy of booster vaccinations in reducing reinfection is currently under debate.

Antibody response and risk of reinfection over 2 years among the patients with first wave of COVID-19

OBJECTIVES

To describe the dynamics and factors related to natural and hybrid humoral response against the SARS-CoV-2 and risk of reinfection among first-wave patients.

METHODS

A prospective longitudinal study with periodic serological follow-up after acute onset of all recovered patients with SARS-CoV-2 infection cared in Udine Hospital (March-May 2020). Nucleocapsid (N) protein and spike receptor-binding domain (S-RBD) antibody tests were used to distinguish natural and vaccine-induced response.

RESULTS

Overall, 153 patients (66 men, mean age 56 years) were followed for a median of 27.3 (interquartile range 26.9-27.8) months. Seroreversion was 98.5% (95% CI: 96.8-99.4) for SARS-CoV-2-N IgM at 1 year and 57.4% (95% CI: 51.5-63.5) for SARS-CoV-2-N IgG at 2 years. Initial serological response (hazard ratio [HR]: 0.99, 95% CI: 0.99-0.99, p 0.002 for IgM and HR: 0.97, 95% CI: 0.97-0.98, p < 0.001 for IgG) and severity of acute infection (HR: 0.62, 95% CI: 0.39-0.96, p 0.033 for IgM and HR: 0.60, 95% CI: 0.37-0.99, p < 0.001 for IgG) were independently associated with persistent SARS-CoV-2-N IgM/IgG response. Older age and smoker status were associated with long-term SARS-CoV-2-N IgM and SARS-CoV-2-N IgG, respectively (HR: 0.75, 95% CI: 0.57-0.98, p 0.038; HR: 1.77, 95% CI: 1.19-2.61, p 0.004 respectively). All patients maintained SARS-CoV-2-S-RBD IgG response at 24-month follow-up. Reinfections occurred in 25 of 153 (16.3%) patients, mostly during the omicron circulation. Reinfection rates did not differ significantly between SARS-CoV-2-N IgG seronegative and seropositive patients (14/89, 15.7% vs. 10/62, 16.1%, p 0.947). Unvaccinated patients had higher risk of reinfection (4/7, 57.1% vs. vaccinated 21/146, 14.4%, p 0.014).

DISCUSSION

First-wave patients had durable natural humoral immunity in 40% and anti-S-RBD response in 100% up to 2 years after infection. Natural humoral response alone was not protective against reinfections with omicron SARS-CoV-2 variants, whereas vaccination was effective to reduce the risk of a new infection.

Possible temporal relationship between SARS-CoV-2 infection and anti-NMDA receptor encephalitis: a meta-analysis

The global impact of SARS-CoV-2 infection has raised concerns about secondary diseases beyond acute illness. This review explores the significance and potential underlying mechanisms of how SARS-CoV-2 infection might elicit an immune response targeting N-methyl-D-aspartate (NMDA) receptors, and its implications for autoimmune-driven neuropsychiatric manifestations. We identified 19 published case reports of NMDA receptor encephalitis associated with SARS-CoV-2 infection or vaccination by a systematic literature search. The significance of these reports was limited since it is not clear if a coincidental or causal relationship exists between SARS-CoV-2 infection or vaccination and manifestation of NMDA receptor encephalitis. The included studies were hampered by difficulties in establishing if these patients had pre-existing NMDA receptor antibodies which entered the brain by infection- or vaccination-associated transient blood-brain barrier leakage. In addition, four cases had comorbid ovarian teratoma, which is a known trigger for development of NMDA receptor encephalitis. Considering that billions of people have contracted COVID-19 or have been vaccinated against this virus, the publication of only 19 case reports with a possible link to NMDA receptor encephalitis, indicates that it is rare. In conclusion, these findings do not support the case that SARS-CoV-2 infection or vaccination led to an increase of existing or de novo encephalitis mediated by an autoimmune response targeting NMDA receptor function. Nevertheless, this work underscores the importance of ongoing vigilance in monitoring viral outbreaks and their potential impact on the central nervous system through basic, epidemiological and translational research.

Pulmonary Function and Survival 1 Year After Dupilumab Treatment of Acute Moderate to Severe Coronavirus Disease 2019: A Follow-up Study From a Phase 2a Trial

Background

We previously conducted a phase 2a randomized placebo-controlled trial of 40 subjects to assess the efficacy and safety of dupilumab use in people hospitalized with coronavirus disease 2019 (COVID-19) (NCT04920916). Based on our preclinical data suggesting that downstream pulmonary dysfunction with COVID-19 induced type 2 inflammation, we contacted patients from our phase 2a study at 1 year for assessment of post-COVID-19 conditions.

Methods

Subjects at 1 year after treatment underwent pulmonary function tests, high-resolution computed tomographic imaging, symptom questionnaires, neurocognitive assessments, and serum immune biomarker analysis, with subject survival also monitored. The primary outcome was the proportion of abnormal diffusion capacity for carbon monoxide (DLCO) or 6-minute walk test (6MWT) at the 1-year visit.

Results

Of those survivors who consented to 1-year visits (n = 16), subjects who had originally received dupilumab were less likely than those who received placebo to have an abnormal DLCO or 6MWT (Fisher exact P = .011; adjusted P = .058). As a secondary endpoint, we saw that 16% of subjects in the dupilumab group died by 1 year compared to 38% in the placebo group, though this was not statistically significant (log-rank P = .12). We did not find significant differences in neurocognitive testing, symptoms, or chest computed tomography between treatment groups but observed a larger reduction in eotaxin levels in those who received dupilumab.

Conclusions

In this observational study, subjects who received dupilumab during acute COVID-19 hospitalization were less likely to have a reduced DLCO or 6MWT, with a nonsignificant trend toward reduced mortality at 1 year compared to placebo.

An Epidemic Model with Infection Age and Vaccination Age Structure

A model of epidemic dynamics is developed that incorporates continuous variables for infection age and vaccination age. The model analyzes pre-symptomatic and symptomatic periods of an infected individual in terms of infection age. This property is shown to be of major importance in the severity of the epidemic, when the infectious period of an infected individual precedes the symptomatic period. The model also analyzes the efficacy of vaccination in terms of vaccination age. The immunity to infection of vaccinated individuals varies with vaccination age and is also of major significance in the severity of the epidemic. Application of the model to the 2003 SARS epidemic in Taiwan and the COVID-19 epidemic in New York provides insights into the dynamics of these diseases. It is shown that the SARS outbreak was effectively contained due to the complete overlap of infectious and symptomatic periods, allowing for the timely isolation of affected individuals. In contrast, the pre-symptomatic spread of COVID-19 in New York led to a rapid, uncontrolled epidemic. These findings underscore the critical importance of the pre-symptomatic infectious period and the vaccination strategies in influencing the dynamics of an epidemic.

Immune response and severity of Omicron BA.5 reinfection among individuals previously infected with different SARS-CoV-2 variants

Introduction

COVID-19 continues to spread worldwide, with an increasing number of individuals experiencing reinfection after recovering from their primary infection. However, the nature and progression of this infection remain poorly understood. We aimed to investigate the immune response, severity and outcomes of Omicron BA.5 reinfection among individuals previously infected with different SARS-CoV-2 variants.

Methods

We enrolled 432 COVID-19 cases who had experienced prior infection with the ancestral SARS-CoV-2 virus, Delta variant or Omicron BA.2 variant between January 2020 and May 2022 in Guangzhou, China. All cases underwent follow-up from March to April, 2023 through telephone questionnaires and clinical visits. Nasal lavage fluid and peripheral blood were collected to assess anti-RBD IgA, anti-RBD IgG and virus-specific IFN-γ secreting T cells.

Results

Our study shows that 73.1%, 56.7% and 12.5% of individuals with a prior infection of the ancestral virus, Delta or Omicron BA.2 variant experienced reinfection with the BA.5 variant, respectively. Fever, cough and sore throat were the most common symptoms of BA.5 reinfection, with most improving within one week and none progressing to a critical condition. Compared with individuals without reinfection, reinfected patients with a prior Delta infection exhibited elevated levels of nasal anti-RBD IgA, serum anti-RBD IgG and IFN-γ secreting T cells, whereas there was no noticeable change in reinfected individuals with a prior BA.2 infection.

Conclusion

These results suggest that BA.5 reinfection is common but severe outcomes are relatively rare. Reinfection with a novel SARS-CoV-2 variant different from the prior infection may induce a more robust immune protection, which should be taken into account during vaccine development.

Humoral response against spike protein enhanced by fifth and sixth COVID-19 mRNA vaccine in the uninfected and infected subjects

Antibody obtained by the coronavirus disease-19 (COVID-19) mRNA vaccine declines over time, and additional vaccinations are offered. It is not clear how repeated vaccination affects humoral immunity in uninfected individuals. We analyzed immunoglobulin G for spike protein (S-IgG) titers in COVID-19 uninfected and infected individuals vaccinated up to six times. The geometric mean S-IgG titers were 575.9 AU/mL and 369.0 AU/mL in those who received 6 and 5 doses less than 180 days after the last vaccination in uninfected subjects. In the 180-360 days after the last vaccination, the geometric mean S-IgG titers were 237.9 AU/mL and 128.6 AU/mL in the uninfected subjects who underwent five-dose and four-dose groups, respectively. Multivariate analysis showed that S-IgG titer increased 1.261-fold with each additional dose of mRNA vaccine. The S-IgG titers were 2.039-fold higher in the COVID-infected subjects compared to uninfected subjects. The positivity rate of nucleocapsid antibodies, suggesting a history of COVID-19, decreased 82% and 30% of COVID-infected cases after 180 and 360 days of infection, respectively. This result suggested that repeated vaccination with the COVID-19 mRNA vaccine may increase antibody titer in uninfected subjects.

Work Attendance with Acute Respiratory Illness Before and During COVID-19 Pandemic, United States, 2018-2022

Both SARS-CoV-2 and influenza virus can be transmitted by asymptomatic, presymptomatic, or symptomatic infected persons. We assessed effects on work attendance while ill before and during the COVID-19 pandemic in the United States by analyzing data collected prospectively from persons with acute respiratory illnesses enrolled in a multistate study during 2018-2022. Persons with previous hybrid work experience were significantly less likely to work onsite on the day before through the first 3 days of illness than those without that experience, an effect more pronounced during the COVID-19 pandemic than during prepandemic influenza seasons. Persons with influenza or COVID-19 were significantly less likely to work onsite than persons with other acute respiratory illnesses. Among persons with positive COVID-19 test results available by the second or third day of illness, few worked onsite. Hybrid and remote work policies might reduce workplace exposures and help reduce spread of respiratory viruses.

Risk of SARS-CoV-2 Reinfection 3 Years after the Start of the Pandemic: A Population-Level Observational Study

The risk of SARS-CoV-2 reinfections changes as new variants emerge, but the follow-up time for most of the available evidence is shorter than two years. This study evaluated SARS-CoV-2 reinfection rates in the total population of an Italian province up to three years since the pandemic's start. This retrospective cohort study used official National Healthcare System data on SARS-CoV-2 testing and vaccinations, demographics, and hospitalizations in the Province of Pescara, Italy, from 2 March 2020 to 31 December 2022. A total of 6541 (5.4%) reinfections and 33 severe and 18 lethal COVID-19 cases were recorded among the 121,412 subjects who recovered from a primary infection. There were no severe events following reinfection in the young population, whereas 1.1% of reinfected elderly died. A significantly higher reinfection risk was observed among females; unvaccinated individuals; adults (30-59 y); and subjects with hypertension, COPD, and kidney disease. Up to three years after a primary SARS-CoV-2 infection, the majority of the population did not experience a reinfection. The risk of severe COVID-19 following a reinfection was very low for young and adult individuals but still high for the elderly. The subjects with hybrid immunity showed a lower reinfection risk than the unvaccinated.

Pulmonary function and survival one year after dupilumab treatment of acute moderate to severe COVID-19: A follow up study from a Phase IIa trial

Background

We previously conducted a Phase IIa randomized placebo-controlled trial of 40 subjects to assess the efficacy and safety of dupilumab use in those hospitalized with COVID-19 (NCT04920916). Based on our pre-clinical data suggesting downstream pulmonary dysfunction with COVID-19 induced type 2 inflammation, we contacted patients from our Phase IIa study at 1 year for assessment of Post Covid-19 Conditions (PCC).

Methods

Subjects at 1 year after treatment underwent pulmonary function testing (PFTs), high resolution computed tomography (HRCT) imaging, symptom questionnaires, neurocognitive assessments, and serum immune biomarker analysis, with subject survival also monitored. The primary outcome was the proportion of abnormal PFTs, defined as an abnormal diffusion capacity for carbon monoxide (DLCO) or 6-minute walk testing (6MWT) at the 1-year visit.

Results

Sixteen of the 29 one-year survivors consented to the follow up visit. We found that subjects who had originally received dupilumab were less likely to have abnormal PFTs compared to those who received placebo (Fisher's exact p=0.011, adjusted p=0.058). We additionally found that 3 out of 19 subjects (16%) in the dupilumab group died by 1 year compared to 8 out of 21 subjects (38%) in the placebo group (log rank p=0.12). We did not find significant differences in neurocognitive testing, symptoms or CT chest imaging between treatment groups but observed evidence of reduced type 2 inflammation in those who received dupilumab.

Conclusions

We observed evidence of reduced long-term morbidity and mortality from COVID-19 with dupilumab treatment during acute hospitalization when added to standard of care regimens.