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.

Hospital-wide antigen screening for coronavirus disease in a tertiary reference center in Sapporo, Japan: A single-center observational study.

ABSTRACT: Hospital-wide screenings for coronavirus disease (COVID-19) are important to identify healthcare workers at risk of exposure. However, the currently available diagnostic tests are expensive or only identify past infection. Therefore, this single-center observational study aimed to assess the positivity rate of hospital-wide antigen screening tests for COVID-19 and evaluate clinical factors associated with antigen positivity during a COVID-19 institutional outbreak in Sapporo, Japan.We analyzed the data of 1615 employees who underwent salivary or nasal swab antigen tests on November 18, 2020, to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Laboratory confirmation using reverse transcriptase polymerase chain reaction was performed for those with positive viral serology. The demographic characteristics, job titles, and risk of contact with COVID-19 patients were compared between employees with and without COVID-19.A total of 19 employees (1.2%) tested positive for the SARS-CoV-2 antigen. The positivity rate was high among rehabilitation therapists (2.1%) and employees in the low-risk contact group (6.1%). Although there was no association between the job titles and the seropositivity rate, those in the low-risk contact group had an increased risk of testing positive for the viral antigen (odds ratio, 8.67; 95% confidence interval, 3.30-22.8).The antigen positivity rate was low during the hospital outbreak, suggesting that risk assessment of exposure to COVID-19 patients may provide more useful information than using job titles to identify infected health care providers.

A single-center comparative analysis of outpatients with and without COVID-19 in Sapporo, Japan.

This study aimed to investigate the demographic, clinical, and epidemiological statistics of Japanese patients attending a designated outpatient clinic for COVID-19 in Sapporo, Japan, and contrast the clinical and epidemiological features between those with and without mild COVID-19. A total of 27 (8.6%) of 315 patients were diagnosed with COVID-19. They had higher proportions of myalgia, direct contact with a confirmed COVID-19 patient, and attendance of social gatherings in close confines. We believe that our study makes a significant contribution to the literature because it provides a clinical picture of mild COVID-19 in the Japanese population, which has not been studied extensively. It can also assist in optimizing the local preventive measures to reduce the transmission of COVID-19.