Safety and efficacy of inactivated COVID-19 vaccines in women vaccinated during the first trimester of pregnancy

OBJECTIVES: This study aimed to investigate the safety of the inactivated COVID-19 vaccines in early pregnant women in view of their adverse-effect profile and associated maternal-fetal complications, as well as to evaluate their immunogenicity. METHODS: In this prospective observational cohort study, 232 women in their first trimester or those in the periconception period who inadvertently received two doses of inactivated COVID-19 vaccine between January 21, 2021, and January 14, 2022 were analyzed. Meanwhile, 735 unvaccinated early pregnancy women were also included in the study at a case-to-control ratio of 1:3. RESULTS: The vaccination group did not have an increased miscarriage rate compared with that of the control group (P = 0.918). Furthermore, the birth defect rates in the vaccine group and control group were 0.83% and 1.0%, respectively. Vaccination did not increase the risk of small for gestational age, gestational diabetes mellitus, preterm, or hypertensive disorders of pregnancy (P >0.01). Within 12 weeks after the second dose, the inactivated vaccine effectively produced neutralizing antibody (NAb) against SARS-CoV-2. The NAb levels in the paired umbilical cord serum and maternal serum samples during delivery were negative in both groups. The T-cell subset remained within the normal range in both groups. CONCLUSION: Therefore, our study proves that inactivated COVID-19 vaccines are safe for mothers and fetuses and also effective in producing NAb against SARS-CoV-2.