ABSTRACT
Background. COVID-19 presents a serious health risk to pregnant people and pregnancy outcomes. However, pregnant people were not included in pivotal phase III COVID-19 vaccine efficacy trials. Methods. We used Cox regression models in a cohort study to determine hazard ratios (HR) of a PCR positive test ("infection") comparing vaccinated with unvaccinated pregnant persons in Kaiser Permanente Northern California. HRs were adjusted for age, race/ethnicity, type of insurance coverage, geographical area, BMI, preexisting diabetes, hypertension, parity, time since pregnancy onset and smoking status. Vaccine effectiveness (VE), calculated as 1 minus adjusted HR, was estimated for fully vaccinated < 150 and >= 150 days prior to infection. VE was estimated for before and during Delta, and Omicron. We also calculated incidence rates of COVID-pneumonia associated hospitalization by vaccination status. Results. Among 68836 pregnancies between 12/15/2020 and 3/31/2022, 21834 (31.7%) were fully vaccinated and 5980 (8.7%) were boosted by the end of pregnancy. Compared with unvaccinated persons, the HRs of infection for fully vaccinated < 150 days prior were 0.13 (95% CI: 0.07 - 0.23;VE=87% [77% - 93%]) before Delta;0.25 (CI: 0.20 - 0.30;VE=75% [70% - 80%]) during Delta and 0.76 (CI: 0.61 - 0.94;VE= 24% [16% - 39%]) during Omicron. The HRs for >= 150 days prior were 0.38 (CI: 0.31 - 0.46;VE=62 % [54% - 69%]) during Delta and 1.04 (CI: 0.89 - 1.22;VE= -0.04% [-0.22% - 0.11%]) during Omicron. The HRs for boosted persons were 0.10 (CI: 0.04 - 0.25;VE= 90% [75% - 96%]) during Delta and 0.42 (CI: 0.34 - 0.52;VE=58% [48% - 66%]) during Omicron periods. Incidence rates (IR) per 1000 person-years for hospitalization before delta were 0.75 among unvaccinated and zero among vaccinated. During Delta, the IR was 6.64 for unvaccinated and zero for fully vaccinated and boosted. During Omicron, the IR was 10.27 for unvaccinated, zero for fully vaccinated < 150 days prior, 2.48 for fully vaccinated >= 150 days prior and zero for those boosted. Conclusion. COVID-19 vaccines protect against infection and hospitalization among pregnant people. However, vaccine effectiveness against infection wanes over time and was lower during Omicron. Booster doses are necessary for continuous protection.
ABSTRACT
COVID-19 vaccination is critical to ending the COVID-19 pandemic. Members of minority racial and ethnic groups have experienced disproportionate COVID-19–associated morbidity and mortality (1);however, COVID-19 vaccination coverage is lower in these groups (2). CDC used data from CDC’s Vaccine Safety Datalink (VSD)* to assess disparities in vaccination coverage among persons aged ≥16 years by race and ethnicity during December 14, 2020–May 15, 2021. Measures of coverage included receipt of ≥1 COVID-19 vaccine dose (i.e., receipt of the first dose of the Pfizer-BioNTech or Moderna COVID-19 vaccines or 1 dose of the Janssen COVID-19 vaccine [Johnson And Johnson]) and full vaccination (receipt of 2 doses of the Pfizer-BioNTech or Moderna COVID-19 vaccines or 1 dose of Janssen COVID-19 vaccine). Among 9.6 million persons aged ≥16 years enrolled in VSD during December 14, 2020–May 15, 2021, ≥1-dose coverage was 48.3%, and 38.3% were fully vaccinated. As of May 15, 2021, coverage with ≥1 dose was lower among non-Hispanic Black (Black) and Hispanic persons (40.7% and 41.1%, respectively) than it was among non-Hispanic White (White) persons (54.6%). Coverage was highest among non-Hispanic Asian (Asian) persons (57.4%). Coverage with ≥1 dose was higher among persons with certain medical conditions that place them at higher risk for severe COVID-19 (high-risk conditions) (63.8%) than it was among persons without such conditions (41.5%) and was higher among persons who had not had COVID-19 (48.8%) than it was among those who had (42.4%). Persons aged 18–24 years had the lowest ≥1-dose coverage (28.7%) among all age groups. Continued monitoring of vaccination coverage and efforts to improve equity in coverage are critical, especially among populations disproportionately affected by COVID-19. VSD is a collaboration between CDC’s Immunization Safety Office and eight integrated health care organizations in six U.S. states.† VSD captures information on COVID-19 vaccine doses administered, regardless of where they are received, based on an automated search within the organizations’ facilities (outpatient and inpatient records) and external systems (e.g., health insurance claims and state or local immunization What is already known about this topic? Non-Hispanic Black and Hispanic persons experience higher COVID-19–associated morbidity and mortality, yet COVID-19 vaccination coverage is lower in these groups. What is added by this report? As of May 15, 2021, 48.3% of persons identified in CDC’s Vaccine Safety Datalink aged ≥16 years had received ≥1 COVID-19 vaccine dose and 38.3% were fully vaccinated. Coverage with ≥1 dose was lower among non-Hispanic Black (40.7%) and Hispanic persons (41.1%) than among non-Hispanic White persons (54.6%);coverage was highest (57.4%) among non-Hispanic Asian persons. What are the implications for public health practice? Continued monitoring of vaccination coverage and efforts to improve equity in vaccination coverage are critical, especially among populations disproportionately affected by COVID-19. © 2021 Department of Health and Human Services. All rights reserved.