Objective: To investigate the incidence of adverse events following immunization (AEFI) of human papillomavirus (HPV) vaccines in Hangzhou City from 2017 to 2021, so as to provide insights into safety monitoring and evaluation for HPV vaccines. Methods: The AEFI caused by immunization of bivalent (HPV2), quadrivalent (HPV4) and nonavalent HPV vaccines (HPV9) reported in Hangzhou City from 2017 to 2021 were captured from the AEFI Surveillance Module of Chinese Disease Control and Prevention Information System, and HPV vaccination data were captured from the Zhejiang Municipal Immunization Information Management System. The incidence, temporal distributions and clinical symptoms of AEFI were analyzed. Results: Totally 922 310 doses of HPV vaccines were immunized in Hangzhou City from 2017 to 2021, and 232 cases with AEFI were reported, with an overall incidence rate of 25.15/105 doses. The reported incidence rates of AEFI caused by HPV2, HPV4 and HPV9 vaccination were 31.13/105 doses, 25.93/105 doses and 22.01/105 doses, respectively. General reactions and abnormal reactions were predominant AEFI, and the reported incidence rates of general reactions and abnormal reactions were 21.58/105 doses and 2.60/105 dose, respectively. AEFI predominantly occurred 0 to 1 day post-immunization (165 cases, 71.12%), and the main clinical symptoms included local swelling of injection sites, hard tubercle and fever, with reported incidence rates of 10.30/105 doses, 5.96/105 doses and 6.18/105 doses, respectively. Conclusions Low incidence of AEFI was reported following HPV vaccination in Hangzhou City from 2017 to 2021, and all AEFI were mild. The safety of HPV2, HPV4 and HPV9 remains high.

Malignant tumors in children are one of the most important diseases that threaten the health and quality of life of children and are the second most common cause of death in children.With the continuous improvement and progress of treatment technology, the long-term survival rate of children with tumor has been significantly improved, but both the disease itself and the treatment can impair the immune function of children, which makes them vulnerable to various infectious diseases and secondary serious complications, and even become a source of infection, endangering the health of others. Vaccination is the most cost-effective measure to prevent infectious diseases. For children with normal immune functions, the benefits of vaccination usually outweigh the disadvantages. However, there is a lack of detailed data on the vaccination situation, efficacy and safety of vaccine use for such immunocompromised tumor survivors, and there are no authoritative and uniform vaccination recommendations. This article reviewed and summarized the literature and consensus of some domestic and foreign scholars on current status of post-treatment vaccination status, efficacy and safety of vaccination for children with tumors after treatment, with the aim of providing a reference for the practice in this field in China.