biostudies-literatureZerbo OU.S. Department of Health & Human Services | NIH | National Institute of Allergy and Infectious DiseasesU.S. Department of Health & Human Services | NIH | National Institute of Allergy and Infectious Diseases (NIAID)894https://www.ebi.ac.uk/biostudies/studies/S-EPMC9974935biostudies-literatureUnknown14(1)We examined the effectiveness of maternal vaccination against SARS-CoV-2 infection in 30,311 infants born at Kaiser Permanente Northern California from December 15, 2020, to May 31, 2022. Using Cox regression, the effectiveness of ≥2 doses of COVID-19 vaccine received during pregnancy was 84% (95% confidence interval [CI]: 66, 93), 62% (CI: 39, 77) and 56% (CI: 34,71) during months 0-2, 0-4 and 0- 6 of a child's life, respectively, in the Delta variant period. In the Omicron variant period, the effectiveness of maternal vaccination in these three age intervals was 21% (CI: -21,48), 14% (CI: -9,32) and 13% (CI: -3,26), respectively. Over the entire study period, the incidence of hospitalization for COVID-19 was lower during the first 6 months of life among infants of vaccinated mothers compNature communicationsMaternal SARS-CoV-2 vaccination and infant protection against SARS-CoV-2 during the first six months of life.PMC99749351R01AI168373-01Omer SRoss PLayefsky EKlein NPRay GTFireman BGoddard KLewis EZerbo OGreenberg MfalseMaternal SARS-CoV-2 vaccination and infant protection against SARS-CoV-2 during the first six months of life.We examined the effectiveness of maternal vaccination against SARS-CoV-2 infection in 30,311 infants born at Kaiser Permanente Northern California from December 15, 2020, to May 31, 2022. Using Cox regression, the effectiveness of ≥2 doses of COVID-19 vaccine received during pregnancy was 84% (95% confidence interval [CI]: 66, 93), 62% (CI: 39, 77) and 56% (CI: 34,71) during months 0-2, 0-4 and 0- 6 of a child's life, respectively, in the Delta variant period. In the Omicron variant period, the effectiveness of maternal vaccination in these three age intervals was 21% (CI: -21,48), 14% (CI: -9,32) and 13% (CI: -3,26), respectively. Over the entire study period, the incidence of hospitalization for COVID-19 was lower during the first 6 months of life among infants of vaccinated mothers comp2023-01-01T00:00:00Z2023 Feb2025-04-05T13:01:27.087Z2025-02-19T02:21:24.427ZS-EPMC99749353685466010.1038/s41467-023-36547-4