Evaluation of SARS-CoV-2 vaccination in pregnant and breastfeeding women.

Background: : The SARS-CoV-2 virus can lead to adverse pregnancy outcomes; pregnant women also experience immune suppression, increasing vulnerability. Vaccination can confer lasting protection, but most clinical trials exclude pregnant and breastfeeding women, leading to paucity of safety data.

Methods: : Via an online questionnaire, we have inquired about the safety experience of 2192 pregnant or breastfeeding women vaccinated against SARS-CoV-2, including the incidence of adverse events, pregnancy outcomes, and confirmed infection with SARS-CoV-2.

Results: : The incidence of other adverse events was higher in women vaccinated during breastfeeding. Significant differences were observed for fatigue (relative risk 1.230, 95%CI 1.051 to 1.444, p=0.0098), headache (RR 1.822, 95%CI 1.379 to 2.418, p<0.0001), myalgia (RR 1.633, 95%CI 1.269 to 2.110, p<0.0001), chills (RR 2.027, 95%CI, p<0.0001), subfebrile temperature ≤ 38°C (RR 1.697, 95%CI 1.240 to 2.335, p=0.0007), arthralgia (RR 1.924, 95%CI 1.340 to 2.776, p=0.0002), fever > 38°C (R 6.410, 95%CI 2.890 to 14.30, p<0.0001), and shivers (RR 2.204, 95%CI 1.264 to 3.863, p=0.0049). No pattern of SAEs emerged. Menstrual cycle bleeding disorders occurred in 0.7% of breastfeeding women after the first dose and 0.5% after the second dose. One spontaneous abortion occurred; 93.1% of pregnancies were carried to term, 5.6% late preterm, 0.9% moderate preterm, and 0.3% very preterm. Two children had congenital defects. Vaccine efficacy was 96.3%.

Conclusions: : The safety profile of SARS-CoV-2 vaccines in pregnant and breastfeeding women was similar to the general population. Breastfeeding women experienced higher adverse event rates than pregnant women, presumably due to immune suppression in pregnancy.