Surveillance for Adverse Events Following Immunization with Domestic Sabin-Strain Inactivated Poliovirus Vaccine - China, 2015-2022.

INTRODUCTION

Domestic Sabin-strain inactivated poliovirus vaccine (sIPV) was approved for use in China in 2015 and introduced into the national immunization schedule in a sequential schedule with oral poliovirus vaccine (OPV) in May 2016. However, a comprehensive analysis describing the characteristics, occurrences, and incidences of adverse events following immunization (AEFI) with sIPV in China is lacking.

METHODS

Data on sIPV doses administered and AEFI reported from 2015 to 2022 were obtained from the Chinese National Immunization Information System (CNIIS). Descriptive epidemiological methods and statistics were used to analyze and describe the characteristics, occurrences, and incidences of AEFI following sIPV in China from 2015 to 2022.

RESULTS

From 2015 to 2022, over 110,000,000 sIPV doses were administered, and 46,748 sIPV AEFIs were reported, resulting in an AEFI reporting rate of 42.44/100,000. Most AEFIs (46,333, 99.11%) were non-serious. Causality assessment determined 46,061 (98.53%) AEFIs were vaccine product-related reactions, including 44,001 (94.12%) common and 2,060 (4.41%) rare vaccine reactions. Among common vaccine reactions, reporting rates for fever >38.5 °C, local redness and swelling ≥2.6 cm, and local induration ≥2.6 cm were 12.02/100,000, 5.13/100,000, and 1.67/100,000, respectively. Among rare vaccine reactions, reporting rates for anaphylactic rash, thrombocytopenic purpura, and febrile convulsion were 1.56/100,000, 0.09/100,000, and 0.03/100,000, respectively.

CONCLUSIONS

Most reported sIPV AEFIs were non-serious, and the reporting rate of rare vaccine reactions has been very low since sIPV was approved for use in China. As sIPV remains in use in China, surveillance of AEFIs associated with this vaccine needs to be maintained.