Introduction

Oral poliovirus vaccine (OPV) and diphtheria-tetanus-acellular pertussis vaccine (DTaP) are widely used in China while Haemophilus influenzae type b vaccines (Hib) and a DTaP, inactivated poliovirus (IPV) and Hib polysaccharide conjugated to tetanus protein (PRP ~ T) combined vaccine (DTaP–IPV//PRP ~ T) have lower coverage. There are limited safety data on these vaccines in Chinese pediatric populations. Methods: To estimate incidence rates (IRs) of health outcomes of interest (HOIs) among children exposed to OPV, DTaP, Hib, and DTaP–IPV//PRP ~ T, we conducted a retrospective cohort study using a population-based electronic health record (EHR) database in Yinzhou district, Ningbo City. Children 0–2 years of age receiving at least one dose of these vaccines between January 1, 2012 and March 31, 2017 were included in the study. Yinzhou EHR database consisted of immunization records and healthcare data of children from hospitals and community health centers in the district. Eight HOIs (i.e., anaphylaxis, febrile seizures, all seizures, asthma, apnea, Kawasaki disease [KD], urticaria/angioedema, Guillain–Barré syndrome [GBS]) were identified using ICD-10 codes. Results: A total of 220,422 eligible children was identified. No cases of apnea, KD, and GBS were observed within 7 days post-vaccination. During 0–7 days post-vaccination for OPV, DTaP, Hib, and DTaP–IPV//PRP ~ T, the IRs of anaphylaxis, febrile seizures, all seizures, urticaria/angioedema and asthma ranged from 0.0 to 50.0, 0.0 to 99.9, 29.1 to 249.8, 297.8 to 949.1, and 992.7 to 2298.2 per 100,000 person-years, respectively, and 0.0 to 0.9, 0.0 to 1.9, 0.6 to 4.6, 5.6 to 17.5, and 18.7 to 42.3 per 100,000 doses, respectively. Conclusion: IRs of some HOIs in our study were comparable with those in the literature while IRs of other HOIs were not due to differences in study design, post-vaccination risk periods assessed, and vaccine types. Future studies should consider medical chart review for validating HOIs obtained in the EHR.