(C-249) Adverse events following COVID-19 vaccination and SARS-CoV-2 infection in women of reproductive age, United States, 2021-2022

Background: Adverse events following COVID-19 vaccination or SARS-CoV-2 infection in pregnancy are not well documented, nor are variations in these risks between pregnant and non-pregnant populations.

Objectives: We quantified the incidence of adverse events given COVID-19 vaccination or SARS-CoV-2 infection in women of reproductive capability, and examined pregnancy as a potential risk modifier.

Methods: We conducted an exposure-matched cohort study capturing women of reproductive capability, 11 December 2020–30 September 2022 in the United States. COVID-19 vaccination, SARS-CoV-2 infection, and the occurrence medically-attended adverse events (up to 42 days following exposure) were identified from inpatient and outpatient medical claims. Odds ratios for adverse events given exposure were estimated from logistic regressions, with pregnancy included as an effect modifier.

Results: There were 1,007,165 (533,249 pregnant; 471,916 non-pregnant) participants. COVID-19 vaccine coverage was 15.2% and 57.4% among those pregnant and non-pregnant; SARS-CoV-2 incidence was 9.9% and 14.2%, respectively. We identified 2,576 (120.7 per 10,000) adverse events among pregnant participants, with no differences between those vaccinated and unvaccinated (adjusted odds ratio [aOR] 1.04 [95% CI 0.96, 1.13]). Adverse events given vaccination were elevated among non-pregnant participants (aOR 1.19, 95%CI 1.11, 1.28). Difference between pregnant and non-pregnant participants were significant (test of heterogeneity, p=0.011). Neurological events including Guillain-Barre syndrome and seizures and were higher following vaccination among both pregnant and non-pregnant participants. Considerably more adverse events occurred given SARS-CoV-2 infection. Compared to uninfected participants, the odds of myocarditis were very high (pregnant: aOR 10.84, 95% CI 3.40, 34.63); non-pregnant: aOR 14.38, 95%CI 5.34, 38.70), as were the odds of acute myocardial infarction, (pregnant: aOR 3.15, 95%CI 1.56, 6.37; non-pregnant: aOR 4.34, 95% CI 2.79, 6.76). Cases of multisystem inflammatory syndrome were also elevated across both groups following SARS-CoV-2 infection.

Conclusions: Adverse events following COVID-19 vaccination are rare among pregnant and non-pregnant populations. Their incidence is dwarfed by substantially elevated incidence of adverse events following SARS-CoV-2 infection. Uniquely, our study demonstrated that pregnancy does not modify the risk of adverse events given COVID-19 vaccination or SARS-CoV-2 infection. Our findings reinforce the need for sustained COVID-19 vaccination, including during pregnancy.