Abstract
Objective: We aimed to determine antibody titers at six months and their percentage change from three to six months after the second dose of the BNT162b2 coronavirus disease 2019 (COVID-19) mRNA vaccine (Pfizer/BioNTech) and to explore clinical variables associated with titers in Japan. Methods: We enrolled 365 healthcare workers (250 women, 115 men) whose three-month antibody titers were analyzed in our previous study and whose blood samples were collected 183 ± 15 days after the second dose. Participant characteristics, collected previously, were used. The relationships of these factors with antibody titers at six months and percentage changes in antibody titers from three to six months were analyzed. Results: Median age was 44 years. Median antibody titer at six months was 539 U/mL. Older participants had significantly lower antibody titers (20s, 752 U/mL; 60s–70s, 365 U/mL). In age-adjusted analysis, smoking was the only factor associated with lower antibody titers. Median percentage change in antibody titers from three to six months was −29.4%. The only factor significantly associated with the percentage change in Ab titers was not age or smoking, but sex (women, −31.6%; men, −25.1%). Conclusion: The most important factors associated with lower antibody titers at six months were age and smoking, as at three months, probably reflecting their effect on peak antibody titers. However, the only factor significantly associated with the attenuation in Ab titers from three to six months was sex, which reduced the sex difference seen during the first three months. Antibody titers may be affected by different factors at different time points.
Highlights
Introduction distributed under the terms andThe BNT162b2 vaccine (Pfizer/BioNTech), which was the first coronavirus disease2019 (COVID-19) mRNA vaccine to be administered to healthcare professionals in Japan, starting in February 2021, is expected to help to prevent both the onset [1] and progression of COVID-19
We analyzed Ab titers at six months and their percentage change from three to six months after the second dose of the BNT162b2 vaccine and explored the clinical variables associated with these parameters in Japan
We recruited 378 participants whose Ab titers 3 months after the second dose of the BNT162b2 COVID-19 vaccine were already analyzed in our previous study [12]
Summary
Yushi Nomura 1,2 , Michiru Sawahata 1,3, * , Yosikazu Nakamura 4 , Ryousuke Koike 1,2 , Otohiro Katsube 1 , Koichi Hagiwara 3 , Seiji Niho 2 , Norihiro Masuda 5 , Takaaki Tanaka 6 and Kumiya Sugiyama 1,7. Saitama Medical Center, Department of Respiratory Medicine and Clinical Immunology, Dokkyo Medical University, Shimotsuga 321-0293, Japan. Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
