Post-vaccination Adverse Reactions After Receiving the Pfizer-BioNTech Coronavirus Disease 2019 Vaccines Among Healthcare Workers in Sapporo, Japan

Background/objective Although a third dose of the coronavirus disease 2019 vaccine was initiated, the reports of the post-vaccination adverse reactions after dose three from Japan were limited. We aimed to report on post-vaccination adverse reactions to the third dose of the vaccine among healthcare workers and compare the results with those after the first two doses of vaccine at a tertiary medical center in Japan. Materials and methods After each vaccine (Pfizer-BioNTech) administration, healthcare workers answered a Web-based questionnaire for two consecutive days regarding local and systemic adverse reactions and anaphylaxis reactions. Information about those who took antipyretics and analgesics was also collected. Data were collected using Microsoft Forms (Microsoft, Redmond, WA, USA), a web-based questionnaire software. We compared the proportions of post-vaccination adverse reactions among the three doses of vaccine using the chi-squared test. Results A total of 1,990 employees received the first dose in March 2021, 1,988 employees received the second dose in April 2021, and 1,748 employees received the third dose between December 2021 and January 2022. The median age was 32 years and 21% were men. Local and systemic adverse reactions were greater after dose three than those with the primary series, except for nausea and vomiting. Injected site pain, fatigue, and headache were the three most commonly reported adverse reactions throughout the three sessions. A total of four employees developed anaphylaxis reactions. Additionally, 944 and 1,016 employees reported taking antipyretics and analgesics after doses two and three. Conclusions The coronavirus 2019 booster vaccine was safe and well-tolerated. Clinicians should encourage the public to receive the coronavirus 2019 vaccine series.