ABSTRACT
This study was aimed at monitoring the adverse reactions to tozinameran (mRNA vaccine against SARS-CoV-2) in the vaccine recipients, and to investigate factors that might affect the risk of development of these reactions. The adverse events (13 injection-site and systemic reactions) on day 1 (vaccination day), day 2, day 3, day 4, and day 5- were monitored in the employees of Fukuoka City Hospital who were vaccinated at the hospital between March 2021 and April 2021. The severities of the adverse reactions were also investigated. The frequencies of virtually all the adverse reactions were the highest on day 2, both after the first and after the second dose. The incidence of adverse reactions on day 2 after the first (and second) vaccine dose was 86.0% (86.9%) for pain at the injection site, 33.2% (76.9%) for fatigue, 14.3% (56.9%) for headache, 37.0% (57.2%) for myalgia, 5.2% (51.1%) for fever, and 9.3% (43.9%) for joint pain. The proportion of recipients with any adverse reactions on day 5- was significantly higher after the second dose than after the first dose. The incidence of moderate to severe adverse reactions (except for pain and swelling at the injection site, and rash) was also significantly higher after the second dose. Differences in the incidence of adverse reactions by sex, age, and number of doses were observed. In particular, female sex, age 55 years or under, and second vaccine dose were associated with a significantly increased incidence of fatigue and headache. Female sex and second vaccine dose were identified as being consistently associated with an increased frequency of adverse reactions. The results of the present study would be useful for predicting adverse reactions in prospective recipients, and for setting the vaccination day.
ABSTRACT
The pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted in major social and medical problems. As in other countries, Japan has seen community transfer and clusters in cities, long-term care facilities, and hospitals. SARS-CoV-2 infection can be transmitted both from and to healthcare workers and patients. Severe infection events greatly impact the functioning of the medical care system, and under extreme conditions, can lead to collapse of the system. The staff members at medical institutions who are assigned for the treatment of infectious diseases are at an especially high risk of contact with Coronavirus disease 2019 (COVID-19) patients, and it is quite important to evaluate the effectiveness of infection control measures taken at hospitals to prevent nosocomial infection by SARS-CoV-2. Towards this end, we tested serum samples collected from 375 consenting staff members of Fukuoka City Hospital, a medical institution designated as a treatment center for infectious diseases, for SARS-CoV-2 antibodies by three methods. The staff members were grouped by the risk according to their frequency of contact with COVID-19 patients, and by occupation. The effectiveness of the infection control measures adopted by us was evaluated by comparing the antibody-positive rates of the groups. Our analyses revealed that there was only one antibody-positive staff member who had no contact with COVID-19 patients. Our results suggest that the infection control measures adopted at our hospital have been effective. Our results suggest that nosocomial infection with SARS-CoV-2 infection is preventable with by the precautions that we have adopted at our hospital, even in areas of intensive medical intervention, and that the reuse of personal protective equipment (PPE) that had to be implemented during the study period did not have any adverse impact on the spread of the infection. Further improvements of the precautions are needed for continued prevention of infection, depending on the availability of PPE and the accurate route of transmission.