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

To quantify the incidence of adverse events given COVID-19 vaccination and COVID-19 diagnosis in women of reproductive age; to examine pregnancy as a potential risk modifier. 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 non-causal associations between exposures and adverse events were estimated using logistic regression models, with pregnancy incorporated as an effect modifier. We identified 3,556 (120.6 per 10,000) adverse events among pregnant women, with near-identical incidence rates between those unvaccinated and vaccinated given COVID-19 vaccination (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=3,581; 95.5 per 10,000); however, vaccination effects were stronger (90.2 and 101.6 per 10,000; aOR=1.19, 95%CI 1.11,1.28). More adverse events occurred given 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). Adverse events associated with COVID-19 vaccination were rare in women, but substantially elevated given COVID-19 diagnosis. Being pregnant did not increase adverse event risk, reinforcing the safety of COVID-19 vaccination during pregnancy.