Objective To analyze the occurrence of suspected adverse events following immunization （AEFI） after changing the priority vaccination sites of the adsorbed acellular diphtherior-pertussis-tetanus vaccine （hereinafter referred to as DPT vaccine）， so as to provide scientific basis for mass vaccination.

Methods Monitoring data of AEFI for the DPT vaccine in Wujiang District from September 2020 to August 2022 were collected from China's disease prevention and control information system， and the vaccination information of DPT vaccine in all children's vaccination clinics in Wujiang District during the same period was selected. The incidence of AEFI for the DPT vaccine was analyzed and compared.

Results The reported incidence of AEFI was significantly lower in the buttocks than that in other sites （P<0.05）. The reported incidence of AEFI was significantly higher in booster immunization than that in basic immunization （P<0.05）. After inoculation at different sites， the main clinical symptoms of AEFI were local redness and swelling. There were significant differences in the incidence of local redness and swelling， local induration， pruritus and other symptoms （lethargy， abnormal crying， etc.） （P<0.05）. There were significant differences in the severity of local redness and swelling in different sites （P<0.05）. The degree of redness and swelling in the anterolateral thigh was lower than that in other sites （P<0.05）. The local strong reaction of swelling （>5.0 cm） in the deltoid muscle of the upper arm was significantly higher than that in the buttocks （P<0.05）.

Conclusion The DPT vaccine is safe in different parts of the body and is worth popularizing.