Objective  To examine vaccination status of recombinant coronavirus disease 2019 (COVID-19) vaccine (adenovirus type 5 vector) (Ad5-nCoV) and to evaluate the safety of Ad5-nCoV vaccination in Pudong New Area of Shanghai during a period of COVID-19 epidemic for providing evidence to Ad5-nCoV mass vaccination.

  Methods  The data on Ad5-nCoV mass vaccination and on reported adverse events following immunization (AEFI) related to the vaccination in Pudong New Area of Shanghai from May 2021 through February 2022 were extracted from Shanghai Municipal Vaccination Registry Information System and from China Information System for Disease Control and Prevention. Descriptive statistics was performed on the data collected.

  Results  During the 10-month period in the district, totally 246 913 doses of Ad5-nCoV were administrated and 198 AEFI were registered, with a reported AEFI incidence rate of 80.190/100 000 doses. Of all the reported AEFI, 151 (76.26%) were common adverse reactions, followed by 36 (18.18%) of coincidental events and 9 (4.55%) of psychogenic reactions, and only 2 (1.01%) rare adverse reactions were reported. The reported AEFI incidence rate was the lowest among the vaccinees aged 50 – 92 years. Higher reported AEFI rate was observed among the female vaccinees than that among the male vaccinees (112.29 vs. 66.47 per 100 000 doses) and the reported AEFI rate was higher in the vaccinees having the first dose Ad5-nCoV than that in those having the booster dose (89.03 vs. 25.10 per 100 000 doses). Almost all (93.94% , n =186) of the reported AEFI occurred during the day of the vaccination.

  Conclusion  The reported incidence of Ad5-nCoV-related AEFI was higher than that of inactivated COVID-19 vaccine but lower than that of influenza vaccine in the mass vaccination during a COVID-19 epidemic in a district of Shanghai city, suggesting that the AEFI incidence of recombinant novel coronavirus vaccination was within the safety range.