(1055) A multi-state analysis of breakthrough COVID-19 infection by vaccination status in the United States

Previous studies demonstrated reduction in rates of COVID-19 infection for pregnant persons vaccinated against COVID-19 compared to unvaccinated persons. Few studies have investigated the association between COVID-19 vaccination status (unvaccinated, incomplete, and complete) and COVID-19 infection.

Study Design:

We performed a population-based cohort study using the Vizient®clinical database, which included data from 192 hospitals across 38 states. We included pregnant persons who delivered between January 2021-April 2022. Pregnant persons were grouped into three categories: unvaccinated; incompletely vaccinated (one dose of Pfizer or Moderna); or completely vaccinated (one dose of Johnson & Johnson or ≥ two doses of Moderna or Pfizer). Demographics and outcomes were analyzed using standard statistical tests. Multivariable logistic regression models were used to examine the association between vaccination status and breakthrough maternal COVID-19 infection, adjusting for potential confounders, with adjusted odds ratio (aOR) as the measure of treatment effect.

Results:

Of 399,576 persons who met our inclusion criteria, 1,792 were incompletely vaccinated against COVID and 4,007 were completely vaccinated. Participants across three groups varied by age, race, insurance type, region, and most comorbidies (Table 1). There was no difference between groups in rates of multiple gestation or Cesarean delivery. Completely vaccinated persons had a 36% reduction in risk of COVID-19 infection during pregnancy compared to unvaccinated persons (aOR 0.64, 95% CI 0.51-0.81, p < 0.001) (Table 2). Incomplete maternal vaccination did not protect against breakthrough COVID infections (aOR 0.74, 95% CI 0.53-1.02, p = 0.06).

Conclusion: Complete vaccination conferred protection against breakthrough COVID-19 infection, while incomplete vaccination did not. Pregnant women should be encouraged to complete COVID-19 vaccine doses.