Time course of adverse reactions after BNT162b2 vaccination in healthy and allergic disease individuals aged 5–11 years: an observational and historical cohort study (preprint)

Purpose: We aimed to assess whether BNT162b2 vaccination in children meets high safety standards by surveying adverse reactions in healthy and allergic disease individuals aged 5–11 years in Japan throughout seven days following their first and second BNT162b2 vaccination. Methods This was an observational and historical cohort study. The eligibility criteria of study participants included those aged 5–11 years, who received two doses of BNT162b2, with consent by the children and their guardians. We collected data on sex, age, height, weight, blood type, history of BCG vaccination, allergic disease, medication, history of COVID-19 infection and adverse reactions seven days following the first and second BNT162b2 vaccination using a questionnaire. We used previous reports to compare our result with individuals aged 12–15years. Results A total of 421 participants were eligible for this study. Among the 216 patients with allergic disease, 48 (22.2%) had experienced worsening of their chronic diseases, and the frequency of fatigue and dizziness after the second dose was higher than that of healthy individuals. The experience of systemic adverse reactions was associated with asthma. The frequency of headache, diarrhea, fatigue, muscle/joint pain, and fever after the second BNT162b2 vaccination was lower in the individuals aged 5–11 years than in those aged 12–15 years. Fever was the only systemic adverse reaction that lasted longer than five days (1.0% of participants). Conclusions Individuals with allergic diseases, who are potentially susceptible to COVID-19, may experience worsening of their chronic diseases and more frequent adverse reactions after BNT162b2 vaccination than healthy individuals. To ensure that children with allergic diseases receive the vaccine safely, further information needs to be collected.

Waning of humoral immunity and affecting factors after BNT162b2 vaccination: a cohort study with latent growth curve model in Fukushima (preprint)

Measuring long-term antibody titer kinetics and subsequent COVID-19 vaccinations are crucial for identifying vulnerable populations. Our aim was to determine the association between long-term antibody kinetics up to seven months post second vaccination, including peak titers and factors. A three-time survey was performed in 2021 on healthcare workers in Japan to investigate the changes in humoral immunity using chemiluminescence immunoassay. We included participants who completed the second-dose vaccination, the antibody survey for all three terms, and those who were not infected with COVID-19. A latent growth curve model was used to identify the factors affecting the peak titer and decreasing the antibody slope. Overall, 205 eligible participants were included in the final analysis. Of these, the mean titers of immunoglobulin G (IgG) against the spike (S) protein and the neutralizing activity at seven months after the second vaccination decreased to 154.3 AU/ml (8.8% of the peak titer) and 62.1 AU/ml (9.5% of the peak titer), respectively. The growth model of IgG showed that age significantly affected peak titers (p < 0.001); however, a significant difference was not found for the decreasing slope. In conclusion, aging adults had significantly lower peak antibody titers, however age did not relate to decreasing slope.

Factors Associated with COVID-19 Vaccine Booster Hesitancy: a Retrospective Cohort Study, Fukushima Vaccination Community Survey (preprint)

This was a retrospective cohort study, which aimed to investigate the factors associated with hesitancy to receive the third dose of coronavirus disease 2019 (COVID-19) vaccine. A paper-based questionnaire survey was administered to all participants. Accordingly, the study included participants who provided answer in the questionnaire whether they have an intent to receive the third dose of vaccine. Data on sex, age, area of residence, adverse reactions after the second vaccination, whether the third vaccination was desired, and reasons to accept or hesitate booster vaccination were retrieved. Among the 2439 participants with mean (±SD) age of 52.6±18.9 years, and median IgG-S antibody titer of 324.9 (AU/mL), 97.9% of participants indicated their intent to accept a third vaccination dose. The logistic regression revealed that younger age (OR=0.98; 95% CI: 0.96-1.00) and higher antibody level (OR=2.52; 95% CI: 1.27-4.99) are positively associated with the third vaccine hesitancy. The efficacy of the COVID-19 vaccine and concerns about adverse reactions had significant impact on the third vaccination behavior. A rapid increase in the booster dose rate is needed to control the pandemic, and specific approaches should be taken in these groups that are likely to hesitate the third vaccine, subsequently increasing booster contact rate.