Adverse events associated with COVID-19 vaccination or diagnosis among pregnant and non-pregnant women in the United States, 2021-2022

Abstract

Objectives

To quantify the incidence of adverse events after COVID-19 vaccination and COVID-19 diagnosis in women of reproductive age; to examine pregnancy as a potential risk modifier.

Methods

An exposure-matched cohort study of >1 million women, 11 December 2020–30 September 2022, United States. COVID-19 vaccination, COVID-19 diagnoses, and medically-attended adverse events – including immunologic, neurologic, cerebrovascular, thromboembolic, cardiovascular, respiratory, thrombocytopenic, and coagulative events – were identified from inpatient and outpatient medical claims. Exposed participants were matched with up to four unexposed participants on pregnancy and propensity for COVID-19 vaccination (or diagnosis). Odds ratios quantifying the associations between exposures and adverse events were estimated using logistic regression models, with pregnancy incorporated as an effect modifier.

Results

We identified 3556 (120.6 per 10,000) adverse events among pregnant women, with near-identical incidence rates between those unvaccinated and vaccinated against COVID-19 (120.5 and 120.7 per 10,000; adjusted odds ratio [aOR]=1.04 [95% CI: 0.96, 1.13]). The incidence of adverse events was lower among non-pregnant women (n = 3581; 95.5 per 10,000); however, vaccination effects were stronger (90.2 and 101.6 per 10,000 among unvaccinated and vaccinated women, respectively; aOR = 1.19, 95% CI: 1.11, 1.28). More adverse events occurred following COVID-19 diagnosis, including pericarditis (pregnant: aOR = 5.35, 95% CI: 2.24, 12.79; non-pregnant: aOR = 5.57, 95% CI: 3.02, 10.27) and acute myocardial infarction (pregnant: aOR = 3.15, 95% CI: 1.56, 6.37; non-pregnant: aOR = 4.34, 95% CI: 2.79, 6.76).

Conclusion

Adverse events associated with COVID-19 vaccination were rare in women, but substantially elevated following COVID-19 diagnosis. Being pregnant did not increase adverse event risk, reinforcing the safety of COVID-19 vaccination during pregnancy.