Maternal Vaccination and Risk of Hospitalization for Covid-19 among Infants

Natasha B Halasa1, Samantha M Olson1, Mary A Staat1

  • 1From the Division of Pediatric Infectious Diseases, Department of Pediatrics, Vanderbilt University Medical Center, Nashville (N.B.H.); the Covid-19 Response Team, Centers for Disease Control and Prevention (S.M.O., A.M.P., S.M.G., K.N.P., A.P.C., M.M.P.), the Center for Childhood Infections and Vaccines of Children's Healthcare of Atlanta and the Department of Pediatrics, Emory University School of Medicine (S.K.), and the Division of Critical Care Medicine, Department of Pediatrics, Emory University School of Medicine, Children's Healthcare of Atlanta (K.M.T.) - all in Atlanta; the Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati (M.A.S.), the Division of Pediatric Critical Care Medicine, Nationwide Children's Hospital, Columbus (K.E.B.), and the Division of Critical Care Medicine, Department of Pediatrics, Akron Children's Hospital, Akron (R.A.N.) - all in Ohio; the Department of Anesthesiology, Critical Care, and Pain Medicine, Boston Children's Hospital (M.M.N., A.G.R.), and the Departments of Anaesthesia and Pediatrics, Harvard Medical School (A.G.R.) - both in Boston; the Division of Infectious Diseases, Children's Hospital Los Angeles, and the Departments of Pediatrics and Molecular Microbiology and Immunology, University of Southern California, Los Angeles, Los Angeles (P.S.P.), the Division of Pediatric Hospital Medicine, UC San Diego-Rady Children's Hospital, San Diego (M.A.C.), the Department of Pediatrics, Divisions of Critical Care Medicine and Allergy, Immunology, and Bone Marrow Transplant, University of California, San Francisco, San Francisco (M.S.Z.), and the Division of Critical Care Medicine, UCSF Benioff Children's Hospital, Oakland (N.Z.C.) - all in California; the Department of Pediatrics, Baylor College of Medicine, Immunization Project, Texas Children's Hospital, Houston (J.A.B., L.C.S.); the Division of Critical Care Medicine, Department of Anesthesiology and Critical Care, Children's Hospital of Philadelphia, Philadelphia (K.C.); the Department of Pediatrics, Division of Infectious Diseases, University of Mississippi Medical Center, Jackson (C.V.H.); the Department of Pediatrics, Section of Critical Care Medicine, University of Colorado School of Medicine, and Children's Hospital Colorado, Aurora (A.B.M.); the Division of Critical Care Medicine, Department of Pediatrics, Northwestern University Feinberg School of Medicine, Ann and Robert H. Lurie Children's Hospital of Chicago, Chicago (B.M.C., K.N.M.); the Division of Pediatric Critical Care Medicine, Children's Hospital of Michigan, Central Michigan University, Detroit (S.M.H.), and the Division of Pediatric Critical Care Medicine, Department of Pediatrics, Mott Children's Hospital and University of Michigan, Ann Arbor (H.R.F.); the Section of Pediatric Critical Care, Department of Pediatrics, Arkansas Children's Hospital, Little Rock (K.I.); the Division of Pediatric Critical Care Medicine (E.H.M.), and the Department of Pediatrics (L.S.), Medical University of South Carolina, Charleston; the Department of Pediatrics, University of North Carolina at Chapel Hill Children's Hospital, Chapel Hill (S.P.S., T.C.W.); the Division of Pediatric Critical Care, Department of Pediatrics, Cooperman Barnabas Medical Center, Livingston, NJ (S.J.G.); the Division of Pediatric Infectious Diseases, Department of Pediatrics, Children's Mercy Kansas City, Kansas City, Missouri (J.E.S.); the Ryan White Center for Pediatric Infectious Disease and Global Health, Department of Pediatrics, Indiana University School of Medicine, Indianapolis (S.S.B.); the Department of Pediatrics, Division of Critical Care Medicine, University of Texas Southwestern, Children's Medical Center, Dallas (M.M.); the Division of Pediatric Critical Care, University of Minnesota Masonic Children's Hospital, Minneapolis (J.R.H.), and the Divisions of Pediatric Infectious Diseases and Pediatric Critical Care Medicine, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester (E.R.L.) - both in Minnesota; the Division of Pediatric Critical Care, Department of Pediatrics, University of Utah, Salt Lake City (H.C.); the Department of Pediatrics, Division of Cardiology, Louisiana State University Health Sciences Center and Children's Hospital of New Orleans, New Orleans (T.T.B.); the Division of Pediatric Critical Care, Department of Pediatrics, Children's Hospital and Medical Center, Omaha, NE (M.L.C.); and the Division of Pediatric Critical Care Medicine, Department of Pediatrics, University of Alabama at Birmingham, Birmingham (M.K.).

Insights

Maternal COVID-19 vaccination during pregnancy significantly reduced infant hospitalizations for coronavirus disease 2019. This protection was observed against both Delta and Omicron variants, highlighting the importance of vaccination for vulnerable infants.

Area of Science:

  • Immunology
  • Pediatrics
  • Public Health

Background:

  • Infants under 6 months face high COVID-19 complication risks and are ineligible for vaccination.
  • Maternal antibodies transferred transplacentally after COVID-19 vaccination may protect infants.

Purpose of the Study:

  • To assess the effectiveness of maternal COVID-19 vaccination during pregnancy against infant hospitalization.
  • To evaluate protection conferred during the Delta and Omicron variant surges.

Main Methods:

  • A case-control test-negative study design was employed.
  • Infants hospitalized with and without COVID-19 were compared.
  • Vaccine effectiveness was estimated based on maternal vaccination status during pregnancy.

Main Results:

  • Maternal vaccination showed 52% overall effectiveness against infant hospitalization for COVID-19.
  • Effectiveness was higher during the Delta variant surge (80%) than Omicron (38%).
  • Vaccination after 20 weeks of gestation yielded higher effectiveness (69%) compared to earlier vaccination (38%).

Conclusions:

  • Maternal mRNA vaccination significantly reduced the risk of COVID-19 hospitalization in infants younger than 6 months.
  • This protection extended to critical illness, underscoring the benefit for this vulnerable population.
Abstract

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