Analyses of reported severe adverse events after immunization with SARS-CoV-2 vaccines in the United States: One year on

Avidity maturation of anti-spike IgG after vaccination in COVID-19 convalescent vs COVID-19 naïve patients

Antibodies and avidity maturation contribute to long-lasting immunity, and previous COVID-19 seems to enhance the immune response after vaccination. The aim of this study was to compare the immune response after vaccination between COVID-19 convalescents and naïve patients. Blood samples from COVID-19 convalescents and naïve patients, taken 1, 3 and 6 months after the second dose of vaccine (mRNA-vaccine BNT162b2), were analysed for anti-spike IgG and avidity. Questionnaires concerning side effects were used. Thirty-one patients in the COVID-19 cohort and 30 patients in the naïve cohort were included. High levels of anti-spike IgG and avidity index were seen. Anti-spike IgG were significantly higher in the COVID-19 cohort and declining (median 1250, 566, 282 RU/ml vs 565, 187, 65 RU/ml). Avidity did not change over time (median at 6 months 78% vs 65%). The most common side effects were pain at the injection site, malaise and headache. In conclusion, high levels of anti-spike IgG after vaccination were seen and most patients developed high-avidity antibodies, although antibody levels and avidity were higher in the COVID-19 cohort. Over time, the levels of anti-spike IgG declined, yet avidity remained high. Side effects did not differ between groups and were of short duration.

Reported rates of all-cause serious adverse events following immunization with BNT-162b in 5-17-year-old children in the United States

Vaccine development against COVID-19 has mitigated severe disease. However, reports of rare but serious adverse events following immunization (sAEFI) in the young populations are fuelling parental anxiety and vaccine hesitancy. With a very early season of viral illnesses including COVID-19, respiratory syncytial virus (RSV), influenza, metapneumovirus and several others, children are facing a winter with significant respiratory illness burdens. Yet, COVID-19 vaccine and booster uptake remain sluggish due to the mistaken beliefs that children have low rates of severe COVID-19 illness as well as rare but severe complications from COVID-19 vaccine are common. In this study we examined composite sAEFI reported in association with COVID-19 vaccines in the United States (US) amongst 5-17-year-old children, to ascertain the composite reported risk associated with vaccination. Between December 13, 2020, and April 13, 2022, a total of 467,890,599 COVID-19 vaccine doses were administered to individuals aged 5-65 years in the US, of which 180 million people received at least 2 doses. In association with these, a total of 177,679 AEFI were reported to the Vaccine Adverse Event reporting System (VAERS) of which 31,797 (17.9%) were serious. The rates of ED visits per 100,000 recipients were 2.56 (95% CI: 2.70-3.47) amongst 5-11-year-olds, 18.25 (17.57-18.95) amongst 12-17-year-olds and 33.74 (33.36-34.13) amongst 18-65-year olds; hospitalizations were 1.07 (95% CI 0.87-1.32) per 100,000 in 5-11-year-olds, 6.83 (6.42-7.26) in 12-17-year olds and 8.15 (7.96-8.35) in 18-65 years; life-threatening events were 0.14 (95% CI: 0.08-0.25) per 100,000 in 5-11-year olds, 1.22 (1.05-1.41) in 12-17-year-olds and 2.96 (2.85-3.08) in 18-65 year olds; and death 0.03 (95% CI 0.01-0.10) per 100,000 in 5-11 year olds, 0.08 (0.05-0.14) amongst 12-17-year olds and 0.76 (0.71-0.82) in 18-65 years age group. The results of our study from national population surveillance data demonstrate rates of reported serious AEFIs amongst 5-17-year-olds which appear to be significantly lower than in 18-65-year-olds. These low risks must be taken into account in overall recommendation of COVID-19 vaccination amongst children.

The Incidence and Effect of Adverse Events Due to COVID-19 Vaccines on Breakthrough Infections: Decentralized Observational Study With Underrepresented Groups

Background

Despite continuing efforts to improve the inclusion of underserved groups in clinical research, gaps in diversity remain. Participation of special populations is especially important when facing problems of unprecedented complexity such as the COVID-19 pandemic. A better understanding of factors associated with the immune response in diverse populations would advance future preventive and curative approaches.

Objective

The objective of this study was to investigate the factors potentially responsible for adverse events following COVID-19 immunization. The study population included adults from rural areas, transitional countries, and those with medically understudied conditions, across a broad age range.

Methods

The study evolved from peer support networks developed during the COVID-19 pandemic. Participants were recruited digitally through online neighborhood and health communities. Some of the participants volunteered as study investigators assisting with offline recruitment and safety monitoring. Individuals who consented to participate were asked to share their vaccination experiences either using constantly evolving web-based surveys or via one-on-one communication. Inferential statistical analysis to estimate differences between study groups was performed using parametric and nonparametric tests.

Results

Of 1430 participants who shared their vaccination experiences, 648 had outcome measures at their 1.5-year follow-up. Significant differences were found between age groups, types of vaccine adverse events (VAEs), incidences of breakthrough infections, and health conditions linked to the microbiome. Pairwise comparisons showed that VAEs interfering with daily activities were significantly higher in both younger (18-59 years) and older age groups (80-100 years, P<.001) than in the 60-79–year age group. Short-term VAEs were associated with lower incidence of breakthrough COVID-19 infections relative to those who reported either minimal or long-term adverse events (P<.001). A genetic origin was suggested for some adverse reactions.

Conclusions

The findings of this study demonstrate that vaccine adverse reactions in older individuals are being overlooked, and the incidence of VAEs impairing immunity may be higher than previously perceived. Better preventive measures are needed for all those at risk for life-threatening and long-term adverse events due to vaccination. Supportive community-based studies focusing on these populations could add important data to the current body of knowledge. Further and more comprehensive studies should follow.

Trial Registration

ClinicalTrials.gov NCT04832932; https://clinicaltrials.gov/ct2/show/NCT04832932

International Registered Report Identifier (IRRID)

RR2-10.1101/2021.06.28.21256779