Related Experiment Video
Updated: Sep 7, 2025

Induction of Maternal Immune Activation in Mice at Mid-gestation Stage with Viral Mimic PolyI:C
Published on: March 25, 2016
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.
Background:
Infants younger than 6 months of age are at high risk for complications of coronavirus disease 2019 (Covid-19) and are not eligible for vaccination. Transplacental transfer of antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) after maternal Covid-19 vaccination may confer protection against Covid-19 in infants.
Methods:
We used a case-control test-negative design to assess the effectiveness of maternal vaccination during pregnancy against hospitalization for Covid-19 among infants younger than 6 months of age. Between July 1, 2021, and March 8, 2022, we enrolled infants hospitalized for Covid-19 (case infants) and infants hospitalized without Covid-19 (control infants) at 30 hospitals in 22 states. We estimated vaccine effectiveness by comparing the odds of full maternal vaccination (two doses of mRNA vaccine) among case infants and control infants during circulation of the B.1.617.2 (delta) variant (July 1, 2021, to December 18, 2021) and the B.1.1.259 (omicron) variant (December 19, 2021, to March 8, 2022).
Results:
A total of 537 case infants (181 of whom had been admitted to a hospital during the delta period and 356 during the omicron period; median age, 2 months) and 512 control infants were enrolled and included in the analyses; 16% of the case infants and 29% of the control infants had been born to mothers who had been fully vaccinated against Covid-19 during pregnancy. Among the case infants, 113 (21%) received intensive care (64 [12%] received mechanical ventilation or vasoactive infusions). Two case infants died from Covid-19; neither infant's mother had been vaccinated during pregnancy. The effectiveness of maternal vaccination against hospitalization for Covid-19 among infants was 52% (95% confidence interval [CI], 33 to 65) overall, 80% (95% CI, 60 to 90) during the delta period, and 38% (95% CI, 8 to 58) during the omicron period. Effectiveness was 69% (95% CI, 50 to 80) when maternal vaccination occurred after 20 weeks of pregnancy and 38% (95% CI, 3 to 60) during the first 20 weeks of pregnancy.
Conclusions:
Maternal vaccination with two doses of mRNA vaccine was associated with a reduced risk of hospitalization for Covid-19, including for critical illness, among infants younger than 6 months of age. (Funded by the Centers for Disease Control and Prevention.).
More Related Videos
09:09Generating a Reproducible Model of Mid-Gestational Maternal Immune Activation using PolyI:C to Study Susceptibility and Resilience in Offspring
Published on: August 17, 2022
13:00Intranasal Immunization and Milk Collection in Studies of Maternal Immunization in New Zealand White Rabbits Oryctolagus cuniculus
Published on: July 31, 2021
Related Concept Videos
Vaccinations
Development of Immunocompetence
The initial cells that migrate from the fetal thymus settle within the skin and epithelial tissues lining the mouth, digestive tract, and in females, the uterus and vagina. These cells, including skin-based dendritic cells, serve as antigen-presenting cells, playing a key role in T cell activation.
Subsequent T...
Transcytosis of IgG
IgG molecules from a mother undergo transcytosis starting around 13 weeks of gestation. The amount of IgG transferred and entering the fetal blood circulation increases with...
Active versus Passive Immunity
Active Immunity
Active immunity refers to the resistance one develops...
Pneumonia V: Nursing management and Prevention
The nurse must practice strict medical asepsis and adhere to infection control guidelines to minimize healthcare-associated infections.
Enhance airway patency
Position the patient correctly to facilitate drainage of the affected lung segments. Manual or mechanical percussion and vibration can also be employed....
Teratogenicity