Surveillance for adverse events following immunization of diphtheria, tetanus and acellular pertussis combined vaccine in Gansu, 2016−2022

Objective To understand characteristics of adverse events following immunization (AEFI) of diphtheria, tetanus and acellular pertussis (DTaP) combined vaccine in Gansu province from 2016 to 2022 and evaluate the safety of the vaccine.

Methods The incidence data of AEFI and vaccination information were collected through the immunization planning information management system for a descriptive epidemiological analysis.

Results A total of 22 674 AEFI of DTaP vaccine were reported in Gansu from 2016 to 2022, the reported incidence of AEFI was 259.24/100 000 doses. In AEFI cases, most reactions were general ones, accounting for 99.71%, and more boy babies were affected. The ratio of boy babies to girl babies is 1.26:1. And the cases aged 18-24 months (34.32%) and 3-5 months (33.35%) accounted for higher proportion. No seasonality and monthly distribution were observed (the concentration M is 0.17). The adverse reactions mainly occurred within 1 day after the vaccination. The abnormal reaction was mainly allergic rash(48.48%), and no suspicious signals of abnormal reactions were found in recent years.

Conclusion DTaP is safe, and AEFI prognosis is good, it is necessary to further strengthen the surveillance for AEFI, and improve the capability of causal correlation assessment in Gansu.