The incidences of vaccine-preventable diseases (VPDs) included in the Expanded Program on Immunization in China have decreased significantly in recent decades.

This study summarizes the national incidences of nine VPDs and the seroprevalence of hepatitis B surface antigen (HBsAg) under different immunization strategies from 1950 through 2021 in China. The sharpest decreases in VPD incidence and under-5-year HBsAg seroprevalence occurred during the latest stage of the National Immunization Program. The decreases in VPD incidence were most prominent among children under five years of age.

These findings provide valuable insights for vaccine value assessment and emphasize the importance of implementing immunization strategies in targeted populations.

Detecting poliovirus infections proves to be highly challenging due to their asymptomatic nature and infectious potential, highlighting the crucial importance of effective detection methods in the context of polio eradication efforts. In many countries, including China, the primary approach for identifying polio outbreaks has been through acute flaccid paralysis (AFP) surveillance. In this study, we conducted an evaluation spanning three decades (1993–2022) to assess the effectiveness of AFP surveillance in China.

Data on all AFP cases identified since 1993 and national-level AFP surveillance system quality indicators aligned with the World Health Organization (WHO) standards were collected for analysis. The quality indicators assess surveillance sensitivity, completeness, timeliness of detection notification, case investigation, and laboratory workup. Surveillance sensitivity is determined by the non-polio AFP (NPAFP) detection rate among children under 15 years of age.

Between 1993 and 2022, a total of 150,779 AFP cases were identified and reported. Within this pool, surveillance identified 95 cases of wild poliovirus (WPV) and 24 cases due to vaccine-derived poliovirus. From 1995 onwards, the detection rate of NPAFP cases consistently adhered to the WHO and national standards of ≥1 case per 100,000, falling between 1.38 and 2.76. Starting in 1997, all timeliness indicators consistently achieved the criteria of 80%, apart from the consistency in meeting standards set for the rate of positive specimens sent to the national laboratory.

AFP surveillance has been instrumental in China’s accomplishment of maintaining a polio-free status. The ongoing adherence to key performance indicators, ensuring sensitivity and prompt specimen collection, demonstrates that AFP surveillance is proficient in detecting poliovirus in China. As we move into the post-eradication phase, AFP surveillance remains crucial for the sustained absence of polioviruses in the long term.

The current study aims to assess the performance of data mining techniques in detecting safety signals for adverse events following immunization (AEFI) using routinely obtained data in China. Four different methods for detecting vaccine safety signals were evaluated.

The AEFI data from 2011 to 2015 was collected for our study. We analyzed the data using four different methods to detect signals: the proportional reporting ratio (PRR), reporting odds ratio (ROR), Bayesian confidence propagation neural network (BCPNN), and multi-item gamma Poisson shrinker (MGPS). Each method was evaluated at 1–3 thresholds for positivity. To assess the performance of these methods, we used the published signal rates as gold standards to determine the sensitivity and specificity.

The number of identified signals varied from 602 for PRR1 (with a threshold of 1) to 127 for MGPS1. When considering the common reactions as the reference standard, the sensitivity ranged from 0.9% for MGPS1/2 to 38.2% for PRR1/2, and the specificity ranged from 85.2% for PRR1 and ROR1 to 96.7% for MGPS1. When considering the rare reactions as the reference standard, PRR1, PRR2, ROR1, ROR2, and BCPNN exhibited the highest sensitivity (73.3%), while MGPS1 exhibited the highest specificity (96.9%).

For common reactions, the sensitivities were modest and the specificities were high. For rare reactions, both the sensitivities and specificities were high. Our study provides valuable insights into the selection of signal detection methods and thresholds for AEFI data in China.