COVID vaccination during pregnancy protects infants from hospitalization during their first 6 months of life.

Published in Pediatrics, the study offers valuable insights for clinicians engaging in discussions with pregnant patients about the benefits of vaccination.

“The flu and COVID-19 vaccine have historically been recommended to protect mom, and Tdap and RSV [respiratory syncytial virus] were given to mom to benefit the baby,” said Luke A. Gatta, MD, assistant professor of obstetrics and gynecology at Vanderbilt University Medical Center in Nashville, Tennessee, who was not involved with the study. “Now, we know these lines are blurred because she’s also protecting her baby in those first 6 months of life by getting the COVID-19 vaccine.”

Prior studies have shown that messenger RNA (mRNA) vaccines are safe and effective in pregnancy and protect infants from hospitalizations due to COVID.

“Maternal antibodies are transported across the placenta after vaccination in pregnancy and may protect the infant in the vulnerable first months after birth,” said Helena Niemi Eide, MD, MPH, researcher in the Department of Community Medicine and Global Health at the University of Oslo in Oslo, Norway, who led the study.

Hospitalization rates for COVID are highest among infants younger than 6 months than any other age group younger than 75 years. These infants are especially vulnerable to severe infection and cannot receive a COVID vaccine until they are 6 months old.

Eide and her team conducted a register-based cohort study of hospitalization rates among infants whose mothers were vaccinated for COVID (n = 37,013) and those whose mothers were not vaccinated (n = 109,018). They linked these births to records in the Norwegian Immunisation Registry and the national surveillance system for communicable diseases.

Infants were excluded if their gestational age was less than 22 weeks, they had a birth weight under 500 g, or they were born to mothers who had received a non-mRNA vaccine.

During the first 2 months of life, infants of vaccinated mothers were half as likely to need hospital care for COVID as offspring of unvaccinated mothers (hazard ratio [HR], 0.48; 95% CI, 0.40-0.56). But by 5 months of age, the risk was about 24% lower (HR, 0.76; 95% CI, 0.60-0.98). After 6 months, the findings were statistically insignificant.

As of March 7, 2026, 11% of pregnant women at the time had received the vaccine, according to the CDC. Gatta said clinicians should mention the window of protection for infants when counseling pregnant patients.

“Vaccines help to minimize the risk of hospitalization and serious illness for both mom and baby: I would encourage any mom who might be unsure about vaccines in pregnancy to always talk to their doctor,” Gatta said.

The study was funded by the University of Oslo, NordForsk, and The Research Council of Norway. Study authors reported having no relevant financial disclosures.

Carie Behounek is a health and science writer based in Denver.