Adverse reactions and attitudes toward vaccines among young populations one month after receiving a second dose of mRNA-1273 in Japan.

To investigate adverse reactions and attitudes toward the vaccine during the first month after mRNA- 1273 vaccination in a larger sample including younger men and women in Japan, we distributed a 1-month post-vaccination questionnaire using a Google form to 8,566 people who received a second dose of mRNA-1273 at Okayama University. The response rate was about 40.2% (3,447 responses), the sex ratio was about the same, and 73.3 % (2,528 respondents) were students in their twenties or younger. Poisson regression with robust variance was performed to calculate the prevalence ratio of each symptom by different attributes. The most common adverse reactions after the second vaccine dose were local pain (80.4%), fever (85.1%), malaise (82.0%), headache (64.0%), and chills (57.4%). Approximately 99% of respondents reported that their adverse reactions resolved within 1 week. Over 80% of respondents were satisfied with their vaccination (87.2%), expressed interest in receiving the third vaccination (83.3%), and would recommend vaccination to their loved ones (80.2%). However, among them, 22.0% (757 respondents) would recommend and 28.4% (980 respondents) also stated that they would consider the type of vaccine in these decisions.

Early-stage antibody kinetics after the third dose of BNT162b2 mRNA COVID-19 vaccination measured by a point-of-care fingertip whole blood testing.

Amid the Coronavirus Disease 2019 pandemic, we aimed to demonstrate the accuracy of the fingertip whole blood sampling test (FWT) in measuring the antibody titer and uncovering its dynamics shortly after booster vaccination. Mokobio SARS-CoV-2 IgM & IgG Quantum Dot immunoassay (Mokobio Biotechnology R&D Center Inc., MD, USA) was used as a point-of-care FWT in 226 health care workers (HCWs) who had received two doses of the BNT162b2 mRNA vaccine (Pfizer-BioNTech) at least 8 months prior. Each participant tested their antibody titers before and after the third-dose booster up to 14-days. The effect of the booster was observed as early as the fourth day after vaccination, which exceeded the detection limit (> 30,000 U/mL) by 2.3% on the fifth day, 12.2% on the sixth day, and 22.5% after the seventh day. Significant positive correlations were observed between the pre- and post-vaccination (the seventh and eighth days) antibody titers (correlation coefficient, 0.405; p < 0.001). FWT is useful for examining antibody titers as a point-of-care test. Rapid response of antibody titer started as early as the fourth day post-vaccination, while the presence of weak responders to BNT162b2 vaccine was indicated.

Examining the association between vaccine reactogenicity and antibody titer dynamics after the third dose of BNT162b2 vaccine using a mixed-effects model

Background To mitigate the COVID-19 pandemic, many countries have recommended the use of booster vaccinations. The relationship between the degree of adverse vaccine reactions and elevated antibody titers is of interest;however, no studies have investigated the temporal changes in antibody titers based on repeated measurements after a third dose of the BNT162b2 vaccine. Methods This prospective longitudinal cohort study was conducted with 62 healthcare workers who received a third dose of the BNT162b2 at Okayama University Hospital, Japan. Venous blood draw and fingertip whole blood test sample collection were conducted at the early (3–13 days) and 1-month time points;only FWT sample collection was conducted at the 2-month time point. Information on adverse reactions within 1 week after vaccination was also obtained. The association between fever of 37.5 °C or higher and antibody titers after the third dose of BNT162b2 was examined using a mixed-effects model and Poisson regression with robust variance. Results A trend toward higher antibody titers in the early period after vaccination was observed in the febrile individuals, but the differences were not significant at 1 and 2 months post-vaccination (the partial regression coefficient for fever was 8094.3 [-1910.2, 18,098.8] at 1 month after vaccination, and 1764.1 [-4133.9, 7662.1] at 2 months after vaccination in the adjusted models). Conclusion The findings suggest that the presence of fever after the third vaccine does not predict a sustained elevation in serum antibody titers.

Timing of REGEN-COV administration and progression to severe COVID-19.

INTRODUCTION: Several clinical trials have demonstrated that REGEN-COV (casirivimab and imdevimab) decreases the risk of hospitalization and death among COVID-19 patients. However, these trials did not evaluate the optimal timing of its administration, and evidence is limited regarding the relationship between the timing of administration and progression to severe COVID-19 among patients who receive REGEN-COV in a real-world setting. We examined the association between the timing of REGEN-COV administration and progression to severe COVID-19 among patients who received REGEN-COV in Japan. METHODS: We included a total of 342 COVID-19 patients (37 hospitals) who received REGEN-COV between July 19 and September 30, 2021. We calculated the difference between the date of symptom onset and the date of administration as an indicator of the timing of REGEN-COV administration and determined progression to severe COVID-19 after REGEN-COV administration. We conducted a logistic regression analysis, adjusting for potential confounders. RESULTS: The proportion of cases progressing to severe COVID-19 increased daily from symptom onset and sharply increased from day 5 of onset. The early administration (days 0-4) decreased the risk of progression to severity compared with late administration (after day 5), with an adjusted odds ratio of 0.29 (95% confidence interval: 0.11-0.56). CONCLUSIONS: The early administration of REGEN-COV was associated with a decreased risk of progression to severe COVID-19 when the delta variant was dominant. The present epidemiological findings indicate that this monoclonal antibody therapy should be implemented very early in the clinical course probably even for emerging variants such as omicron BA.2.