Attention all expecting mothers, a new study published in JAMA Pediatrics shows that infants younger than six months born to vaccinated moms during pregnancy were protected from flu-related emergency department visits and hospitalizations. Infants are at higher risk of being hospitalized than other children but can’t get a flu shot until they turn six months. This study underscores the importance of pregnant people getting vaccinated since they are, along with their infants, at higher risk of being hospitalized with flu.
The study in JAMA Pediatrics looked at data from the New Vaccine Surveillance Network (NVSN) from the 2016-2017 through the 2019-2020 flu seasons and found that:
- Flu vaccination during pregnancy reduced the risk of flu in infants younger than six months by one-third.
- Maternal vaccine effectiveness increased with the severity of infant disease, reducing the risk of emergency department visits in infants by about 20 percent and reducing the risk of hospitalization by about 40 percent.
- Protection was most significant among infants younger than three months, reducing the risk of flu-related hospitalizations or emergency department visits by half.
- Maternal vaccine effectiveness was higher in infants born to mothers vaccinated later during their pregnancy.
According to the study, a Flu vaccination during pregnancy is safe and protects both pregnant people and their infants. A previous study has shown that flu vaccination during pregnancy reduced the risk of flu illness in pregnant people by about half. This estimate was similar to other estimates of flu vaccine effectiveness in adult populations during the same season. Maternal vaccination protects infants from flu because the pregnant person passes antibodies to their developing baby. Other studies have also shown similar results: flu vaccination during pregnancy protects against flu illnesses and flu-related hospitalizations in infants during their first few months.
NVSN includes seven pediatric medical institutions across the United States and conducts population-based surveillance in infants and children with acute respiratory illness and acute gastroenteritis. For this observational study, NVSN analyzed data from more than 3,700 infants, with a little more than half of the mothers vaccinated during pregnancy. Influenza virus infection during pregnancy is associated with an increased risk of hospitalization, and some studies have found an association with some adverse birth outcomes. However, according to CDC data systems, flu vaccination among pregnant people is concerningly low and has fallen by 10 to 15 percentage points since the COVID-19 pandemic.