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. 2022 Sep 1;5(9):e2233273.
doi: 10.1001/jamanetworkopen.2022.33273.

Estimation of COVID-19 mRNA Vaccine Effectiveness Against Medically Attended COVID-19 in Pregnancy During Periods of Delta and Omicron Variant Predominance in the United States

Stephanie J Schrag  1 , Jennifer R Verani  1 , Brian E Dixon  2   3 , Jessica M Page  4 , Kristen A Butterfield  5 , Manjusha Gaglani  6   7 , Gabriela Vazquez-Benitez  8 , Ousseny Zerbo  9 , Karthik Natarajan  10   11 , Toan C Ong  12 , Victoria Lazariu  5 , Suchitra Rao  12 , Ryan Beaver  6 , Sascha R Ellington  1 , Nicola P Klein  9 , Stephanie A Irving  13 , Shaun J Grannis  2   14 , Salome Kiduko  5 , Michelle A Barron  12 , John Midturi  6 , Monica Dickerson  1 , Ned Lewis  9 , Melissa S Stockwell  11   15   16 , Edward Stenehjem  4 , William F Fadel  2   3 , Ruth Link-Gelles  1 , Kempapura Murthy  6 , Kristin Goddard  9 , Nancy Grisel  4 , Nimish R Valvi  2 , Bruce Fireman  9 , Julie Arndorfer  4 , Deepika Konatham  6 , Sarah Ball  5 , Mark G Thompson  1 , Allison L Naleway  13
Affiliations

Estimation of COVID-19 mRNA Vaccine Effectiveness Against Medically Attended COVID-19 in Pregnancy During Periods of Delta and Omicron Variant Predominance in the United States

Stephanie J Schrag et al. JAMA Netw Open. .

Abstract

Importance: Pregnant people are at high risk for severe COVID-19 but were excluded from mRNA vaccine trials; data on COVID-19 vaccine effectiveness (VE) are needed.

Objective: To evaluate the estimated effectiveness of mRNA vaccination against medically attended COVID-19 among pregnant people during Delta and Omicron predominance.

Design, setting, and participants: This test-negative, case-control study was conducted from June 2021 to June 2022 in a network of 306 hospitals and 164 emergency department and urgent care (ED/UC) facilities across 10 US states, including 4517 ED/UC encounters and 975 hospitalizations among pregnant people with COVID-19-like illness (CLI) who underwent SARS-CoV-2 molecular testing.

Exposures: Two doses (14-149 and ≥150 days prior) and 3 doses (7-119 and ≥120 days prior) of COVID-19 mRNA vaccine (≥1 dose received during pregnancy) vs unvaccinated.

Main outcomes and measures: Estimated VE against laboratory-confirmed COVID-19-associated ED/UC encounter or hospitalization, based on the adjusted odds ratio (aOR) for prior vaccination; VE was calculated as (1 - aOR) × 100%.

Results: Among 4517 eligible CLI-associated ED/UC encounters and 975 hospitalizations, 885 (19.6%) and 334 (34.3%) were SARS-CoV-2 positive, respectively; the median (IQR) patient age was 28 (24-32) years and 31 (26-35) years, 537 (12.0%) and 118 (12.0%) were non-Hispanic Black and 1189 (26.0%) and 240 (25.0%) were Hispanic. During Delta predominance, the estimated VE against COVID-19-associated ED/UC encounters was 84% (95% CI, 69% to 92%) for 2 doses within 14 to 149 days, 75% (95% CI, 5% to 93%) for 2 doses 150 or more days prior, and 81% (95% CI, 30% to 95%) for 3 doses 7 to 119 days prior; estimated VE against COVID-19-associated hospitalization was 99% (95% CI, 96% to 100%), 96% (95% CI, 86% to 99%), and 97% (95% CI, 79% to 100%), respectively. During Omicron predominance, for ED/UC encounters, the estimated VE of 2 doses within 14 to 149 days, 2 doses 150 or more days, 3 doses within 7 to 119 days, and 3 doses 120 or more days prior was 3% (95% CI, -49% to 37%), 42% (95% CI, -16% to 72%), 79% (95% CI, 59% to 89%), and -124% (95% CI, -414% to 2%), respectively; for hospitalization, estimated VE was 86% (95% CI, 41% to 97%), 64% (95% CI, -102% to 93%), 86% (95% CI, 28% to 97%), and -53% (95% CI, -1254% to 83%), respectively.

Conclusions and relevance: In this study, maternal mRNA COVID-19 vaccination, including booster dose, was associated with protection against medically attended COVID-19. VE estimates were higher against COVID-19-associated hospitalization than ED/UC visits and lower against the Omicron variant than the Delta variant. Protection waned over time, particularly during Omicron predominance.

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Conflict of interest statement

Conflict of Interest Disclosures: Dr Dixon reported receiving personal fees from Elsevier and Springer Nature and grants from the US Centers for Disease Control and Prevention (CDC) outside the submitted work. Dr Gaglani reported receiving grants from CDC–Abt Associates Baylor Scott & White Health during the conduct of the study and grants from CDC Baylor Scott & White Health, CDC–Abt Associates Baylor Scott & White Health, CDC–Vanderbilt University Medical Center, CDC–Westat Baylor Scott & White Health, and Janssen Baylor Scott & White Health outside the submitted work. Dr Vazquez-Benitez reported having a contract with the CDC during the conduct of the study and receiving grants from Sanofi outside the submitted work. Dr Natarajan reported receiving grants from the CDC during the conduct of the study. Dr Rao reported receiving grants from the CDC during the conduct of the study and grants from Biofire outside the submitted work. Dr Klein reported receiving grants from the CDC during the conduct of the study and grants from Pfizer, Merck, GlaxoSmithKline, Sanofi Pasteur, and Protein Science (now Sanofi Pasteur) outside the submitted work. Dr Irving reported receiving grants from the CDC to her institution, through a contract mechanism with Westat, during the conduct of the study and outside the submitted work. Dr Stockwell reported receiving grants from the CDC to Trustees of Columbia during the conduct of the study. Dr Stenehjem reported receiving grants from the CDC during the conduct of the study and outside the submitted work. Dr Fadel reported receiving grants from the CDC during the conduct of the study and outside the submitted work. Dr Goddard reported receiving grants from the CDC during the conduct of the study. Dr Grisel reported receiving grants from Intermountain Healthcare during the conduct of the study. Dr Arndorfer reported receiving grants from the CDC during the conduct of the study. Dr Ball reported receiving contractual support from the CDC during the conduct of the study. Dr Naleway reported receiving grants from the CDC during the conduct of the study and grants from Pfizer and Vir Biotechnology outside the submitted work. No other disclosures were reported.

Figures

Figure 1.
Figure 1.. mRNA COVID-19 Vaccine Effectiveness (VE) Against Laboratory-Confirmed COVID-19–Associated Emergency Department and Urgent Care Encounters Among Pregnant People and Nonpregnant Women, VISION Network, 10 States, June 1, 2021, to June 2, 2022
The VISION Network includes Baylor Scott & White Health (Texas), Columbia University Irving Medical Center (New York), HealthPartners (Minnesota and Wisconsin), Intermountain Healthcare (Utah), Kaiser Permanente Northern California (California), Kaiser Permanente Northwest (Oregon and Washington), Regenstrief Institute (Indiana), and University of Colorado (Colorado). Vaccinated pregnant people included in this analysis received at least their most recent dose during pregnancy; among those with 3 doses, 3 participants during Delta and 1 during Omicron received dose 3 less than 150 days after dose 2, and none of these 4 had documented immunocompromised status. Among vaccinated nonpregnant people with 3 doses, 273 in the Delta period and 324 in the Omicron period received the third dose less than 150 days after the second dose. VE was calculated as described in the Methods section. VE could not be calculated for vaccination during pregnancy during the Delta period among individuals who received 3 doses of mRNA vaccine 120 or more days because the stratum included fewer than 20 encounters with prior vaccination. CLI indicates COVID-19–like illness.
Figure 2.
Figure 2.. mRNA COVID-19 Vaccine Effectiveness (VE) Against Laboratory-Confirmed COVID-19–Associated Hospitalizations Among Pregnant People and Nonpregnant Women, VISION Network, 10 States, June 1, 2021, to June 2, 2022
The VISION Network includes Baylor Scott & White Health (Texas), Columbia University Irving Medical Center (New York), HealthPartners (Minnesota and Wisconsin), Intermountain Healthcare (Utah), Kaiser Permanente Northern California (California), Kaiser Permanente Northwest (Oregon and Washington), Regenstrief Institute (Indiana), and University of Colorado (Colorado). Vaccinated pregnant people included in this analysis received at least their most recent dose during pregnancy; among individuals with 3 doses, only 2 received the third dose less than 150 days after the second dose. Among vaccinated nonpregnant women with 3 doses, 130 in the Delta period and 43 in the Omicron period received the third dose less than 150 days after the second dose. VE was calculated as described in the Methods section. VE could not be calculated for the individuals during the Delta period who received 3 doses of mRNA vaccine 120 or more days prior to hospitalization because the stratum included fewer than 20 encounters with prior vaccination. CLI indicates COVID-19–like illness.
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