A post-marketing safety surveillance study on vaccines in Chongqing, China from 2006 to 2021: Using a nationwide spontaneous reporting database with multiple data mining methods.

The Chinese National Adverse Events Following Immunization Information System (CNAEFIS) is the national-level passive vaccine safety surveillance system. This study aims to identify post-marketing vaccine adverse reaction signals in Chongqing through systematic analysis of 15-year AEFI data, verify the safety profile of locally recommended vaccines, and provide localized evidence for clinical practice and immunization policy formulation. The study included all 36 marketed vaccines in mainland China and collected all rare adverse reactions (RAR) reported in Chongqing through CNAEFIS from 2006 to 2021. Proportional Reporting Ratio (PRR), Reporting Odds Ratio (ROR), Bayesian Confidence Propagation Neural Network (BCPNN), and Empirical Bayes Gamma-Poisson Shrinker (GPS) were employed to mine potential safety signals within the database. From 2006 to 2021, approximately 90.1 million vaccine doses were recorded in Chongqing, China, and 20,195 individual cases of Adverse Events Following Immunization (AEFIs) were reported. Of these, 3,110 cases (15.4%) were linked to RAR, at an incidence rate of 32.2 per 100,000 doses. Allergic reactions were the most prevalent, with 2,743 cases (88.2% of the RAR), and the Measles-Rubella Vaccine (MR) had the highest IR of allergic reactions, reaching 267.1 cases per 100,000 doses administered. A total of 23 suspicious signals were identified through the combined use of PRR, ROR, GPS, and BCPNN methods. The corresponding clinical diagnoses were mainly non-serious diseases such as angioedema, Henoch-Schönlein purpura, and local abscess. The warning signals of severe diseases such as anaphylactic shock and laryngeal edema, which could be life-threatening due to improper clinical treatment, were weak. The overall safety of vaccines in Chongqing is satisfactory. Vaccine manufacturers should optimize the production process to enhance vaccine tolerability.