A Retrospective Analysis of COVID-19 mRNA Vaccine Breakthrough Infections - Risk Factors and Vaccine Effectiveness

Correlation of COVID-19 vaccination and RT-PCR ct value among cases in Addis Ababa, Ethiopia: implication for future preparedness

BACKGROUND

The COVID-19 disease requires accurate diagnosis to effectively manage infection rates and disease progression. The study aims to assess the relationship between vaccination status and RT-PCR cycle threshold (Ct) values by comparing clinical, RDT and RT-PCR results.

METHODS

A total of 453 suspected COVID-19 cases were included in this study. Nasopharyngeal swabs were collected for both RDT and RT-PCR testing, with RDTs conducted on-site and RT-PCR at the Ethiopian Public Health Institute (EPHI) genomics laboratory. Detailed clinical, RDT, and RT-PCR results were analyzed. Data analysis included descriptive statistics, cross-tabulation, and Chi-Square tests to investigate the connections between diagnostic outcomes and vaccination status, with a focusing on Ct values.

RESULTS

RDT results showed 34.0% negative and 65.8% positive, while RT-PCR results indicated 35.8% negative and 64.2% positive cases. The discrepancies between RDT and RT-PCR results emphasize the importance of thorough testing. No significant association was found between vaccination status and viral load, as indicated by Ct values. Among RT-PCR positive cases, 49.8% had been vaccinated, suggesting challenges in interpreting results among vaccinated individuals. Further analysis revealed that vaccination (first or second dose) had minimal impact on Ct values, indicating limited influence of vaccination status on viral load dynamics in infected individuals.

CONCLUSIONS

The study highlights the significant differences between RDT and RT-PCR outcomes, underscoring the need for a comprehensive testing approach. Additionally, the findings suggest that vaccination status does not significantly impact RT-PCR Ct values, complicating the interpretation of diagnostic results in vaccinated individuals, especially in breakthrough infections and potential false positives.

Presenting clinical symptoms of post-COVID-19 breakthrough infection: Predictors of mortality in a Middle Eastern population

Objective

Breakthrough COVID-19 infections are common following immunisation with various types of vaccines. The patterns of infections have not been well established. We aimed to analyse the signs and symptoms of post vaccination infections in addition to the need for hospital admission, ER visit and supplemental oxygen in relation to age and gender.

Methods

A cross-sectional cohort study was conducted in JUH from March 2021 to August 2022, we interviewed 1479 individuals who are >15 years of age and got a breakthrough infection. The statistical analysis was performed using STATA statistical software.

Results

Out of the 1479 cases, 50.2 % and 69.4 % were females and less than 45 years of age respectively. Symptoms of cough, fever and headache were reported by nearly 50 % of the patients, while one-third complained of dyspnoea. We found that participants older than 45 years had worse clinical outcomes (P-value < 0.001). 13 deaths were identified in this study due to breakthrough infection, 92.3 % of them were older than 45 years (P-value < 0.001). Participants ≥45 years who experienced a breakthrough infection of COVID-19 were 0.7 times less likely to be females using adjusted logistic regression.

Conclusion

This study indicates that despite more severe symptoms reported in younger patients, the major clinical outcomes were worse among older patients, which makes age a major risk for poor outcomes regardless of symptoms. Thus, older people should be evaluated carefully when presenting with mild symptoms of COVID-19 breakthrough infection. The study also confirms that there is no difference in the incidence of COVID-19 breakthrough infections between males and females. Prospective studies are needed to risk stratify COVID-19 breakthrough infections, which should take into account variants of the virus and comorbidities.

COVID-19 breakthrough infections among people living with and without HIV: A statewide cohort analysis

OBJECTIVES

This study aims to characterize and compare COVID-19 breakthrough infections between people living with and without HIV across different phases of the pandemic.

METHODS

Using statewide HIV cohort data, the study population included adult residents in South Carolina (SC) (>18 years old) who were fully vaccinated between January 02, 2021 and April 14, 2022 when Alpha, Delta, and Omicron variants were circulating in SC. We used the Cox proportional hazard model to investigate the association between HIV infection and breakthrough infection, adjusting for relevant covariates.

RESULTS

Among 2,144,415 vaccinated individuals, 8,335 were people living with HIV (PLWH) and 2,136,080 were people without HIV (PWoH). After propensity score matching, HIV infection was not significantly associated with breakthrough infection rate. However, when comparing breakthrough infections among individuals without any booster dose, PLWH had a higher risk of breakthrough infections (adjusted Hazard Ration: 1.19; 95% confidence interval: 1.03-1.39). Compared to PWoH, PLWH with high levels of clusters of differentiation 4 (CD4) count or viral suppression were not associated with breakthrough infections.

CONCLUSIONS

Our findings do not support a broad conclusion that COVID-19 vaccine effectiveness is lower among PLWH, while we did find that PLWH had a higher risk of breakthrough infection compared to PWoH if they did not receive a booster dose.

COVID-19 Vaccination experience in patients with Rheumatoid Arthritis treated at a single VA Medical Center

Background

Following the introduction of the COVID-19 vaccines, there has been uncertainty as to whether receiving the COVID-19 vaccine will result in overactivation of the immune system and subsequently lead to an autoimmune disease flare.

The purpose of this study was to assess whether rheumatoid arthritis (RA) patients who received the mRNA COVID-19 vaccine are at increased risk for disease flare.

Methods

We conducted a single-center retrospective and prospective study at the Louis Stokes Cleveland VA Medical Center between 12/2021 and 2/2022. We included 100 patients with rheumatoid arthritis (RA) who were actively on immunosuppressive therapy and received three doses of the Pfizer-BioNTech vaccine. A survey questionnaire was used to collect data about their RA and if they developed symptoms post vaccination. Our primary end point was to determine incidence of flare of RA after COVID-19 vaccine. Secondary end points were to estimate the side effect profile from the vaccine, and to check if patients developed a COVID-19 infection after they received the vaccine.

Results

None of the patients reported symptoms of RA flare within two months of receiving the 3 doses of the vaccine. Most common vaccine side effects were soreness over the injection site (n=14), headache (n=11), fatigue(n=7) and myalgias(n=4). 5 patients developed a COVID-19 infection prior to receiving the vaccine, 8 after being vaccinated, 3 of the 8 within 5 months from the second dose and 5 out of the 8 within 3 months from the third vaccine dose.

Conclusion

RA patients receiving the COVID-19 Pfizer mRNA vaccine do not appear to commonly develop major symptoms, flares or side effects following the vaccine. Further research with larger numbers of patients with rheumatoid arthritis as well as those with other autoimmune disease is needed to better understand the safety and effectiveness of COVID-19 vaccine.

COVID-19 Breakthrough Infection Among Vaccinated Population in the United Arab Emirates

BACKGROUND

Despite significant efforts to contain the Coronavirus Disease 2019 (COVID-19) pandemic through mass vaccination, numerous nations throughout the world have recorded breakout infections. The incidence and severity of COVID-19 breakthrough infections in the United Arab Emirates (UAE) remain unknown despite extensive COVID-19 vaccine coverage. The goal of this research is to establish the characteristics of COVID-19 breakthrough infections in the UAE's vaccinated population.

METHODS

Between February and March 2022, we conducted a descriptive cross-sectional study in the UAE with 1533 participants to examine the characteristics of COVID-19 breakthrough infection among the vaccinated population.

RESULTS

The vaccination coverage was 97.97%, and the COVID-19 breakthrough infection rate was 32.1%, requiring hospitalization in 7.7% of cases. The bulk of the 492 COVID-19 breakthrough infections reported was among young adults (67%), with the majority experiencing mild to moderate symptoms (70.7%) or remaining asymptomatic (21.5%).

CONCLUSIONS

COVID-19 breakthrough infection were reported in younger age, male sex, non-healthcare professions, vaccination with inactivated whole virus vaccine (Sinopharm), and not receiving a booster dose. Information on breakthrough infection in the UAE might influence public health decisions and motivate measures such as providing additional booster doses of the vaccines to the people.

Breath-holding physiology, radiological severity and adverse outcomes in COVID-19 patients: A prospective validation study

BACKGROUND AND OBJECTIVE

COVID-19 remains a major cause of respiratory failure, and means to identify future deterioration is needed. We recently developed a prediction score based on breath-holding manoeuvres (desaturation and maximal duration) to predict incident adverse COVID-19 outcomes. Here we prospectively validated our breath-holding prediction score in COVID-19 patients, and assessed associations with radiological scores of pulmonary involvement.

METHODS

Hospitalized COVID-19 patients (N = 110, three recruitment centres) performed breath-holds at admission to provide a prediction score (Messineo et al.) based on mean desaturation (20-s breath-holds) and maximal breath-hold duration, plus baseline saturation, body mass index and cardiovascular disease. Odds ratios for incident adverse outcomes (composite of bi-level ventilatory support, ICU admission and death) were described for patients with versus without elevated scores (>0). Regression examined associations with chest x-ray (Brixia score) and computed tomography (CT; 3D-software quantification). Additional comparisons were made with the previously-validated '4C-score'.

RESULTS

Elevated prediction score was associated with adverse COVID-19 outcomes (N = 12/110), OR[95%CI] = 4.54[1.17-17.83], p = 0.030 (positive predictive value = 9/48, negative predictive value = 59/62). Results were diminished with removal of mean desaturation from the prediction score (OR = 3.30[0.93-11.72]). The prediction score rose linearly with Brixia score (β[95%CI] = 0.13[0.02-0.23], p = 0.026, N = 103) and CT-based quantification (β = 1.02[0.39-1.65], p = 0.002, N = 45). Mean desaturation was also associated with both radiological assessment. Elevated 4C-scores (≥high-risk category) had a weaker association with adverse outcomes (OR = 2.44[0.62-9.56]).

CONCLUSION

An elevated breath-holding prediction score is associated with almost five-fold increased adverse COVID-19 outcome risk, and with pulmonary deficits observed in chest imaging. Breath-holding may identify COVID-19 patients at risk of future respiratory failure.

Third wave COVID-19 delta variant breakthrough infection in a Hispanic-dominant suburb of Miami, Florida: ethical dilemma and vaccination hesitancy

Background and Aims

The peak of the third wave of COVID-19 infection was in the summer (August-September) of 2021, dominated by the Delta variant. Florida was the epicenter of the third wave with more than 151,449 cases in the first week of August with a positivity rate of 20%. The purpose of this study is to identify the percentage of COVID-19 infection in vaccinated patients in a minority population in south Florida and to elucidate the relationship, if any, between demographics and breakthrough infections, the rate of vaccine hesitancy, as well as the willingness to receive the monoclonal antibody REGEN-COV for the treatment of COVID-19.

Methods

This cross-sectional study was performed at the Emergency Department, Larkin Community Hospital Palm Spring Campus, located in Hialeah, the fourth largest city in Florida. Hialeah is dominated (94.7%) by Hispanics and Latinos. This city represents a cross-sectional sample of US cities in general and Florida in specific. We enrolled 127 COVID-19 PCR-positive patients.

Results

The infection in vaccinated patients (breakthrough) was found to be about one in three (34%). Despite the high infection rate and mounting death toll, about 73% of our unvaccinated patients answered no to the question 'knowing the consequences of being infected with COVID-19 and the fact that you are positive, would you have chosen to be vaccinated earlier?' However, about 27% of these patients agreed to receive the vaccine and 20.5% received the monoclonal antibody REGEN-COV.

Conclusions

Our study revealed that vaccine hesitancy in South Florida continues to be a major challenge, especially with the emergence of mutations including Delta plus and Omicron.

Analysis of Severe Illness After Postvaccination COVID-19 Breakthrough Among Adults With and Without HIV in the US

IMPORTANCE

Understanding the severity of postvaccination SARS-CoV-2 (ie, COVID-19) breakthrough illness among people with HIV (PWH) can inform vaccine guidelines and risk-reduction recommendations.

OBJECTIVE

To estimate the rate and risk of severe breakthrough illness among vaccinated PWH and people without HIV (PWoH) who experience a breakthrough infection.

DESIGN, SETTING, AND PARTICIPANTS

In this cohort study, the Corona-Infectious-Virus Epidemiology Team (CIVET-II) collaboration included adults (aged ≥18 years) with HIV who were receiving care and were fully vaccinated by June 30, 2021, along with PWoH matched according to date fully vaccinated, age group, race, ethnicity, and sex from 4 US integrated health systems and academic centers. Those with postvaccination COVID-19 breakthrough before December 31, 2021, were eligible.

EXPOSURES

HIV infection.

MAIN OUTCOMES AND MEASURES

The main outcome was severe COVID-19 breakthrough illness, defined as hospitalization within 28 days after a breakthrough SARS-CoV-2 infection with a primary or secondary COVID-19 discharge diagnosis. Discrete time proportional hazards models estimated adjusted hazard ratios (aHRs) and 95% CIs of severe breakthrough illness within 28 days of breakthrough COVID-19 by HIV status adjusting for demographic variables, COVID-19 vaccine type, and clinical factors. The proportion of patients who received mechanical ventilation or died was compared by HIV status.

RESULTS

Among 3649 patients with breakthrough COVID-19 (1241 PWH and 2408 PWoH), most were aged 55 years or older (2182 patients [59.8%]) and male (3244 patients [88.9%]). The cumulative incidence of severe illness in the first 28 days was low and comparable between PWoH and PWH (7.3% vs 6.7%; risk difference, -0.67%; 95% CI, -2.58% to 1.23%). The risk of severe breakthrough illness was 59% higher in PWH with CD4 cell counts less than 350 cells/μL compared with PWoH (aHR, 1.59; 95% CI, 0.99 to 2.46; P = .049). In multivariable analyses among PWH, being female, older, having a cancer diagnosis, and lower CD4 cell count were associated with increased risk of severe breakthrough illness, whereas previous COVID-19 was associated with reduced risk. Among 249 hospitalized patients, 24 (9.6%) were mechanically ventilated and 20 (8.0%) died, with no difference by HIV status.

CONCLUSIONS AND RELEVANCE

In this cohort study, the risk of severe COVID-19 breakthrough illness within 28 days of a breakthrough infection was low among vaccinated PWH and PWoH. PWH with moderate or severe immune suppression had a higher risk of severe breakthrough infection and should be included in groups prioritized for additional vaccine doses and risk-reduction strategies.

A mRNA Vaccine Encoding for a RBD 60-mer Nanoparticle Elicits Neutralizing Antibodies and Protective Immunity Against the SARS-CoV-2 Delta Variant in Transgenic K18-hACE2 Mice

Two years into the COVID-19 pandemic there is still a need for vaccines to effectively control the spread of novel SARS-CoV-2 variants and associated cases of severe disease. Here we report a messenger RNA vaccine directly encoding for a nanoparticle displaying 60 receptor binding domains (RBDs) of SARS-CoV-2 that acts as a highly effective antigen. A construct encoding the RBD of the Delta variant elicits robust neutralizing antibody response, and also provides protective immunity against the Delta variant in a widely used transgenic mouse model. We ultimately find that the proposed mRNA RBD nanoparticle-based vaccine provides a flexible platform for rapid development and will likely be of great value in combatting current and future SARS-CoV-2 variants of concern.

Nomogram Model for Prediction of SARS-CoV-2 Breakthrough Infection in Fujian: A Case–Control Real-World Study

SARS-CoV-2 breakthrough infections have been reported because of the reduced efficacy of vaccines against the emerging variants globally. However, an accurate model to predict SARS-CoV-2 breakthrough infection is still lacking. In this retrospective study, 6,189 vaccinated individuals, consisting of SARS-CoV-2 test-positive cases (n = 219) and test-negative controls (n = 5970) during the outbreak of the Delta variant in September 2021 in Xiamen and Putian cities, Fujian province of China, were included. The vaccinated individuals were randomly split into a training (70%) cohort and a validation (30%) cohort. In the training cohort, a visualized nomogram was built based on the stepwise multivariate logistic regression. The area under the curve (AUC) of the nomogram in the training and validation cohorts was 0.819 (95% CI, 0.780–0.858) and 0.838 (95% CI, 0.778–0.897). The calibration curves for the probability of SARS-CoV-2 breakthrough infection showed optimal agreement between prediction by nomogram and actual observation. Decision curves indicated that nomogram conferred high clinical net benefit. In conclusion, a nomogram model for predicting SARS-CoV-2 breakthrough infection based on the real-world setting was successfully constructed, which will be helpful in the management of SARS-CoV-2 breakthrough infection.

Analysis of Postvaccination Breakthrough COVID-19 Infections Among Adults With HIV in the United States

Importance

Recommendations for additional doses of COVID-19 vaccines for people with HIV (PWH) are restricted to those with advanced disease or unsuppressed HIV viral load. Understanding SARS-CoV-2 infection risk after vaccination among PWH is essential for informing vaccination guidelines.

Objective

To estimate the rate and risk of breakthrough infections among fully vaccinated PWH and people without HIV (PWoH) in the United States.

Design, Setting, and Participants

This cohort study used the Corona-Infectious-Virus Epidemiology Team (CIVET)-II (of the North American AIDS Cohort Collaboration on Research and Design [NA-ACCORD], which is part of the International Epidemiology Databases to Evaluate AIDS [IeDEA]), collaboration of 4 prospective, electronic health record-based cohorts from integrated health systems and academic health centers. Adult PWH who were fully vaccinated prior to June 30, 2021, were matched with PWoH on date of full vaccination, age, race and ethnicity, and sex and followed up through December 31, 2021.

Exposures

HIV infection.

Main Outcomes and Measures

COVID-19 breakthrough infections, defined as laboratory evidence of SARS-CoV-2 infection or COVID-19 diagnosis after a patient was fully vaccinated.

Results

Among 113 994 patients (33 029 PWH and 80 965 PWoH), most were 55 years or older (80 017 [70%]) and male (104 967 [92%]); 47 098 (41%) were non-Hispanic Black, and 43 218 (38%) were non-Hispanic White. The rate of breakthrough infections was higher in PWH vs PWoH (55 [95% CI, 52-58] cases per 1000 person-years vs 43 [95% CI, 42-45] cases per 1000 person-years). Cumulative incidence of breakthroughs 9 months after full vaccination was low (3.8% [95% CI, 3.7%-3.9%]), albeit higher in PWH vs PWoH (4.4% vs 3.5%; log-rank P < .001; risk difference, 0.9% [95% CI, 0.6%-1.2%]) and within each vaccine type. Breakthrough infection risk was 28% higher in PWH vs PWoH (adjusted hazard ratio, 1.28 [95% CI, 1.19-1.37]). Among PWH, younger age (<45 y vs 45-54 y), history of COVID-19, and not receiving an additional dose (aHR, 0.71 [95% CI, 0.58-0.88]) were associated with increased risk of breakthrough infections. There was no association of breakthrough with HIV viral load suppression, but high CD4 count (ie, ≥500 cells/mm3) was associated with fewer breakthroughs among PWH.

Conclusions and Relevance

In this study, COVID-19 vaccination, especially with an additional dose, was effective against infection with SARS-CoV-2 strains circulating through December 31, 2021. PWH had an increased risk of breakthrough infections compared with PWoH. Expansion of recommendations for additional vaccine doses to all PWH should be considered.

Risk Factors Associated With SARS-CoV-2 Breakthrough Infections in Fully mRNA-Vaccinated Individuals: Retrospective Analysis

BACKGROUND

COVID-19 messenger RNA (mRNA) vaccines have demonstrated efficacy and effectiveness in preventing symptomatic COVID-19, while being relatively safe in trial studies. However, vaccine breakthrough infections have been reported.

OBJECTIVE

This study aims to identify risk factors associated with COVID-19 breakthrough infections among fully mRNA-vaccinated individuals.

METHODS

We conducted a series of observational retrospective analyses using the electronic health records (EHRs) of the Columbia University Irving Medical Center/New York Presbyterian (CUIMC/NYP) up to September 21, 2021. New York City (NYC) adult residences with at least 1 polymerase chain reaction (PCR) record were included in this analysis. Poisson regression was performed to assess the association between the breakthrough infection rate in vaccinated individuals and multiple risk factors-including vaccine brand, demographics, and underlying conditions-while adjusting for calendar month, prior number of visits, and observational days in the EHR.

RESULTS

The overall estimated breakthrough infection rate was 0.16 (95% CI 0.14-0.18). Individuals who were vaccinated with Pfizer/BNT162b2 (incidence rate ratio [IRR] against Moderna/mRNA-1273=1.66, 95% CI 1.17-2.35) were male (IRR against female=1.47, 95% CI 1.11-1.94) and had compromised immune systems (IRR=1.48, 95% CI 1.09-2.00) were at the highest risk for breakthrough infections. Among all underlying conditions, those with primary immunodeficiency, a history of organ transplant, an active tumor, use of immunosuppressant medications, or Alzheimer disease were at the highest risk.

CONCLUSIONS

Although we found both mRNA vaccines were effective, Moderna/mRNA-1273 had a lower incidence rate of breakthrough infections. Immunocompromised and male individuals were among the highest risk groups experiencing breakthrough infections. Given the rapidly changing nature of the SARS-CoV-2 pandemic, continued monitoring and a generalizable analysis pipeline are warranted to inform quick updates on vaccine effectiveness in real time.

Clinical Manifestations of COVID-19 Breakthrough Infections: A Systematic Review and Meta-Analysis

To provide a comparative meta‐analysis and systematic review of the risk and clinical outcomes of coronavirus 2019 (COVID‐19) infection between fully vaccinated and unvaccinated groups. Eighteen studies of COVID‐19 infections in fully vaccinated (“breakthrough infections”) and unvaccinated individuals were reviewed from Medline/PubMed, Scopus, Embase, and Web of Science databases. The meta‐analysis examined the summary effects and between‐study heterogeneity regarding differences in the risk of infection, hospitalization, treatments, and mortality between vaccinated and unvaccinated individuals. he overall risk of infection was lower for the fully vaccinated compared to that of the unvaccinated (relative risk [RR] 0.20, 95% confidence interval [CI]: 0.19−0.21), especially for variants other than Delta (Delta: RR 0.29, 95% CI: 0.13−0.65; other variants: RR 0.06, 95% CI: 0.04−0.08). The risk of asymptomatic infection was not statistically significantly different between fully vaccinated and unvaccinated (RR 0.56, 95% CI: 0.27−1.19). There were neither statistically significant differences in risk of hospitalization (RR 1.06, 95% CI: 0.38−2.93), invasive mechanical ventilation (RR 1.65, 95% CI: 0.90−3.06), or mortality (RR 1.19, 95% CI: 0.79−1.78). Conversely, the risk of supplemental oxygen during hospitalization was significantly higher for the unvaccinated (RR 1.40, 95% CI: 1.08−1.82). Unvaccinated people were more vulnerable to COVID‐19 infection than fully vaccinated for all variants. Once infected, there were no statistically significant differences in the risk of hospitalization, invasive mechanical ventilation, or mortality. Still, unvaccinated showed an increased need for oxygen supplementation. Further prospective analysis, including patients’ risk factors, COVID‐19 variants, and the utilized treatment strategies, would be warranted.

SARS-CoV-2 Vaccine Alpha and Delta Variant Breakthrough Infections Are Rare and Mild but Can Happen Relatively Early after Vaccination

(1) Background: Some COVID-19 vaccine recipients show breakthrough infection. It remains unknown, which factors contribute to risks and severe outcomes. Our aim was to identify risk factors for SCoV2 breakthrough infections in fully vaccinated individuals. (2) Methods: We conducted a retrospective case-control study from 28 December 2020 to 25 October 2021. Data of all patients with breakthrough infection was compared to data of all vaccine recipients in the Canton of Basel-City, Switzerland. Further, breakthrough infections by Alpha- and Delta-variants were compared. (3) Results: Only 0.39% (488/126,586) of all vaccine recipients suffered from a breakthrough infection during the observational period, whereof most cases were asymptomatic or mild (97.2%). Breakthrough infections after full vaccination occurred in the median after 78 days (IQR 47-123.5). Factors with lower odds for breakthrough infection were age (OR 0.987) and previous COVID-19 infection prior to vaccination (OR 0.296). Factors with higher odds for breakthrough infection included vaccination with Pfizer/BioNTech instead of Moderna (OR 1.459), chronic disease (OR 2.109), and healthcare workers (OR 1.404). (4) Conclusions: Breakthrough infections are rare and mild but can occur early after vaccination. This implies that booster vaccination might be initiated earlier, especially for risk groups. Due to new variants emerging repeatedly, continuous monitoring of breakthrough infections is crucial.

Incidence and Risk Factors of COVID-19 Vaccine Breakthrough Infections: A Prospective Cohort Study in Belgium

The objective of this study was to investigate the incidence and risk factors associated with COVID-19 vaccine breakthrough infections. We included all persons ≥18 years that had been fully vaccinated against COVID-19 for ≥14 days, between 1 February 2021 and 5 December 2021, in Belgium. The incidence of breakthrough infections (laboratory confirmed SARS-CoV-2-infections) was determined. Factors associated with breakthrough infections were analyzed using COX proportional hazard models. Among 8,062,600 fully vaccinated adults, we identified 373,070 breakthrough infections with an incidence of 11.2 (95%CI 11.2-11.3)/100 person years. Vaccination with Ad26.COV2.S (HR1.54, 95%CI 1.52-1.56) or ChAdOx1 (HR1.68, 95%CI 1.66-1.69) was associated with a higher risk of a breakthrough infection compared to BNT162b2, while mRNA-1273 was associated with a lower risk (HR0.68, 95%CI 0.67-0.69). A prior COVID-19-infection was protective against a breakthrough infection (HR0.23, 95%CI 0.23-0.24), as was an mRNA booster (HR0.44, 95%CI 0.43-0.45). During a breakthrough infection, those who had a prior COVID-19 infection were less likely to have COVID-19 symptoms of almost all types than naïve persons. We identified risk factors associated with breakthrough infections, such as vaccination with adenoviral-vector vaccines, which could help inform future decisions on booster vaccination strategies. A prior COVID-19 infection lowered the risk of breakthrough infections and of having symptoms, highlighting the protective effect of hybrid immunity.

Fighting the SARS-CoV-2 pandemic requires a global approach to understanding the heterogeneity of vaccine responses

Host genetic and environmental factors including age, biological sex, diet, geographical location, microbiome composition and metabolites converge to influence innate and adaptive immune responses to vaccines. Failure to understand and account for these factors when investigating severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine efficacy may impair the development of the next generation of vaccines. Most studies aimed at identifying mechanisms of vaccine-mediated immune protection have focused on adaptive immune responses. It is well established, however, that mobilization of the innate immune response is essential to the development of effective cellular and humoral immunity. A comprehensive understanding of the innate immune response and environmental factors that contribute to the development of broad and durable cellular and humoral immune responses to SARS-CoV-2 and other vaccines requires a holistic and unbiased approach. Along with optimization of the immunogen and vectors, the development of adjuvants based on our evolving understanding of how the innate immune system shapes vaccine responses will be essential. Defining the innate immune mechanisms underlying the establishment of long-lived plasma cells and memory T cells could lead to a universal vaccine for coronaviruses, a key biomedical priority.

The Safety of mRNA-1273, BNT162b2 and JNJ-78436735 COVID-19 Vaccines: Safety Monitoring for Adverse Events Using Real-World Data

Two mRNA COVID-19 vaccines (mRNA-1273, Moderna; and BNT162b2, Pfizer-BioNTech) and one viral vector vaccine (JNJ-78436735, Janssen/Johnson and Johnson) are authorized in the US to hinder COVID-19 infections. We analyzed severe and common adverse events in response to COVID-19 vaccines using real-world, Vaccine Adverse Effect Reporting System (VAERS) data. From 14 December 2020 to 30 September 2021, 481,172 (50.7 ± 17.5 years, males 27.89%, 12.35 per 100,000 people) individuals reported adverse events (AEs). The median time to severe AEs was 2 days after injection. The risk of severe AEs following the one viral vector vaccine (OR = 1.044, 95% CI = 1.005-1.086) was significantly higher than that after the two mRNA vaccines, and the risk among males (OR = 1.374, 95% CI = 1.342-1.406) was higher than among females, except for anaphylaxis. For common AEs, however, the risk to males (OR = 0.621, 95% CI = 0.612-0.63) was lower than to females. In conclusion, we provided medical insight and clinical guidance about vaccine types by characterizing AEs using real-world data. In particular, COVID-19 mRNA vaccines are safer than viral vector vaccines with regard to coagulation disorders, whereas inflammation-related AEs are lower in the viral vaccine. The risk-benefit ratio of vaccines should be carefully considered, and close monitoring and management of severe AEs is needed.

Roadmap for Sex-Responsive Influenza and COVID-19 Vaccine Research in Older Adults

Sex differences in the immune system are dynamic throughout the lifespan and contribute to heterogeneity in the risk of infectious diseases and the response to vaccination in older adults. The importance of the intersection between sex and age in immunity to viral respiratory diseases is clearly demonstrated by the increased prevalence and severity of influenza and COVID-19 in older males compared to older females. Despite sex and age biases in the epidemiology and clinical manifestations of disease, these host factors are often ignored in vaccine research. Here, we review sex differences in the immunogenicity, effectiveness, and safety of the influenza and COVID-19 vaccines in older adults and the impact of sex-specific effects of age-related factors, including chronological age, frailty, and the presence of comorbidities. While a female bias in immunity to influenza vaccines has been consistently reported, understanding of sex differences in the response to COVID-19 vaccines in older adults is incomplete due to small sample sizes and failure to disaggregate clinical trial data by both sex and age. For both vaccines, a major gap in the literature is apparent, whereby very few studies investigate sex-specific effects of aging, frailty, or multimorbidity. By providing a roadmap for sex-responsive vaccine research, beyond influenza and COVID-19, we can leverage the heterogeneity in immunity among older adults to provide better protection against vaccine-preventable diseases.

Risk of Vaccine Breakthrough SARS-CoV-2 Infection and Associated Factors in Healthcare Workers of Trieste Teaching Hospitals (North-Eastern Italy)

Background: Healthcare workers (HCWs) are particularly exposed to biological risk, including SARS-CoV-2 infection. In order to contrast the current pandemic and alleviate the burden of the disease on the healthcare system, a mass vaccination campaign against COVID-19 has been launched worldwide. Aim To evaluate the impact of COVID-19 vaccination in HCWs exposed to SARS-CoV-2, to describe the clinical presentation of COVID-19 in infected HCWs, and to investigate clinical and occupational risk factors for breakthrough infection. Design: Retrospective cohort study. Methods: The cohort of HCWs of Trieste Hospitals were followed up from 1 March 2020, to 30 November 2021 (21 months). All HCWs were periodically screened for SARS-CoV-2 infection by real-time PCR (RT-PCR) analysis. Clinical data were obtained through routine medical surveillance records. Risk factors for SARS-CoV-2 infection were investigated by univariable as well as multivariable logistic regression analysis. Results: Among 4394 HCWs routinely screened for SARS-CoV-2 by PCR on nasopharyngeal swab, a total of 800 incident cases were identified during the entire study period (1 March 2020 to 30 November 2021). Five hundred and sixty-four cases occurred before, and 236 after the start of the vaccination campaign against COVID-19, of whom 155 received a complete vaccination scheme before SARS-CoV-2 infection. Breakthrough infection was featured by mild or no symptoms and was significantly associated with the male sex, BMI > 25, and diabetes mellitus. Some categories of HCWs (physicians and nurse aids/auxiliary personnel) were at a higher risk of breakthrough infection. Conclusions: Fully vaccinated HCWs were less likely to acquire symptomatic as well as asymptomatic SARS-CoV-2 infection. Risk factors for SARS-CoV-2 infection after a full COVID-19 vaccination scheme included the male gender, diabetes mellitus, and overweight. HCWs with higher exposure to COVID-19 patients were at higher risk of breakthrough infection.

The Population-Wide Risk-Benefit Profile of Extending the Primary COVID-19 Vaccine Course Compared with an mRNA Booster Dose Program

The vaccination program is reducing the burden of COVID-19. However, recently, COVID-19 infections have been increasing across Europe, providing evidence that vaccine efficacy is waning. Consequently, booster doses are required to restore immunity levels. However, the relative risk–benefit ratio of boosters, compared to pursuing a primary course in the unvaccinated population, remains uncertain. In this study, a susceptible-exposed-infectious-recovered (SEIR) transmission model of SARS-CoV-2 was used to investigate the impact of COVID-19 vaccine waning on disease burden, the benefit of a booster vaccine program compared to targeting the unvaccinated population, and the population-wide risk–benefit profile of vaccination. Our data demonstrates that the rate of vaccine efficacy waning has a significant impact on COVID-19 hospitalisations with the greatest effect in populations with lower vaccination coverage. There was greater benefit associated with a booster vaccination strategy compared to targeting the unvaccinated population, once >50% of the population had received their primary vaccination course. The population benefits of vaccination (reduced hospitalisations, long-COVID and deaths) outweighed the risks of myocarditis/pericarditis by an order of magnitude. Vaccination is important in ending the COVID-19 pandemic sooner, and the reduction in hospitalisations, death and long-COVID associated with vaccination significantly outweigh any risks. Despite these obvious benefits some people are vaccine reluctant, and as such remain unvaccinated. However, when most of a population have been vaccinated, a focus on a booster vaccine strategy for this group is likely to offer greater value, than targeting the proportion of the population who choose to remain unvaccinated.

COVID-19 infections post-vaccination by HIV status in the United States

IMPORTANCE

Recommendations for additional doses of COVID vaccine are restricted to people with HIV who have advanced disease or unsuppressed HIV viral load. Understanding SARS-CoV-2 infection risk post-vaccination among PWH is essential for informing vaccination guidelines.

OBJECTIVE

Estimate the risk of breakthrough infections among fully vaccinated people with (PWH) and without (PWoH) HIV in the US.

DESIGN SETTING AND PARTICIPANTS

The Corona-Infectious-Virus Epidemiology Team (CIVET)-II cohort collaboration consists of 4 longitudinal cohorts from integrated health systems and academic health centers. Each cohort identified individuals ≥18 years old, in-care, and fully vaccinated for COVID-19 through 30 June 2021. PWH were matched to PWoH on date fully vaccinated, age group, race/ethnicity, and sex at birth. Incidence rates per 1,000 person-years and cumulative incidence of breakthrough infections with 95% confidence intervals ([,]) were estimated by HIV status. Cox proportional hazards models estimated adjusted hazard ratios (aHR) of breakthrough infections by HIV status adjusting for demographic factors, prior COVID-19 illness, vaccine type (BNT162b2, [Pfizer], mRNA-1273 [Moderna], Jansen Ad26.COV2.S [J&J]), calendar time, and cohort. Risk factors for breakthroughs among PWH, were also investigated.

EXPOSURE

HIV infection.

OUTCOME

COVID-19 breakthrough infections, defined as laboratory evidence of SARS-CoV-2 infection or COVID-19 diagnosis after an individual was fully vaccinated.

RESULTS

Among 109,599 individuals (31,840 PWH and 77,759 PWoH), the rate of breakthrough infections was higher in PWH versus PWoH: 44 [41, 48] vs. 31 [29, 33] per 1,000 person-years. Cumulative incidence at 210 days after date fully vaccinated was low, albeit higher in PWH versus PWoH overall (2.8% versus 2.1%, log-rank p<0.001, risk difference=0.7% [0.4%, 1.0%]) and within each vaccine type. Breakthrough infection risk was 41% higher in PWH versus PWoH (aHR=1.41 [1.28, 1.56]). Among PWH, younger age (18-24 versus 45-54), history of COVID-19 prior to fully vaccinated date, and J&J vaccination (versus Pfizer) were associated with increased risk of breakthroughs. There was no association of breakthrough with HIV viral load suppression or CD4 count among PWH.

CONCLUSIONS AND RELEVANCE

COVID-19 vaccination is effective against infection with SARS-CoV-2 strains circulating through 30 Sept 2021. PWH have an increased risk of breakthrough infections compared to PWoH. Recommendations for additional vaccine doses should be expanded to all PWH.