Preterm children, even those born at gestational ages as late as 36 weeks, are more at risk for serious cases of respiratory syncytial virus (RSV), resulting in severe outcomes such as admission to ICUs, compared to those born at full term.

The findings “add to the evidence that young infants, and especially preterm infants, are at high risk of hospitalization and complications from RSV,” said Daniele Gusland, MD, a pediatric infectious disease physician at UCSF Benioff Children’s Hospitals, who was not associated with the study.

RSV is the leading cause of infant hospitalization in the United States. RSV infections in early life are associated with health consequences such as chronic respiratory disease and asthma later in life.

Researchers conducted a study of 5844 children (56.5% male; 20.8% born preterm) younger than 2 years who were hospitalized with RSV at seven medical centers across the United States between 2016 and 2023. 

Preterm children experienced a greater risk for hospitalization lasting at least 3 days (adjusted risk ratio (aRR), 1.3; 95% CI, 1.2-1.4), ICU admission (aRR, 1.2; 95% CI, 1.1-1.4), and assisted ventilation (aRR, 1.8; 95% CI, 1.3-2.4) compared to children born at full term. 

Infants who were born before 37 weeks of gestation tended to be hospitalized at later ages than those born at full term (median age, 6 vs 4 months; P < .001). Premature children accounted for 8.8% of hospitalizations for RSV at less than 1 month of age but made up 30.1% of hospitalizations by 23 months of age.

More preterm children developed bronchopulmonary dysplasia (BPD ), which is a risk factor for contracting the virus, compared to term children (6.6% vs less than.1%; P < .001). Preterm children with BPD showed heightened risk for hospitalization past 3 days compared to term children (aRR, 2.0; 95% CI, 1.7-2.4), with this elevated risk lasting up until 23 months of age. 

The paper highlights the heightened risk for preterm children born at gestational ages above 29 weeks, said Areej Qadri, MD, a neonatologist and assistant professor in the Department of Pediatrics at Rutgers New Jersey Medical School in Newark, New Jersey, who was not associated with the study. 

Gusland said that the findings support vaccination recommendations from the American Academy of Pediatrics (AAP), which advise administering the RSV vaccine to all infants under 8 months of age, depending on their mother’s vaccination status. An additional dose is advised for infants with chronic lung disease of prematurity or if they have risk factors. 

Earlier this month, the CDC removed the RSV vaccine from the category of “generally recommended for all children” and advised giving it only to high-risk populations. 

The CDC recently defined high risk as any child younger than 8 months whose mother did not receive the vaccination, with a later additional dose recommended for those with chronic lung disease or other risk factors. 

The change to recommending the RSV vaccine to only high-risk children was a move condemned by the AAP, American College of Physicians, and National Foundation for Infectious Diseases.

“Having trained in pediatrics before the introduction of RSV vaccines, I was witness to how cruel and brutal RSV infections are,” Qadri said. “Once these babies are affected, all we can offer is basically supportive. We don’t have any antivirals that we can give them.” 

The CDC’s new recommendations emphasize shared decision-making between clinicians and parents. Educating parents about the virus is essential, said Heidi Moline, MD, a pediatrician and principal investigator of the New Vaccine Surveillance Network at the CDC and an author of the study.

“No parent wants to watch their baby struggle to breathe,” Moline said.

The study was funded by the CDC. None of the sources in this article reported any financial conflicts of interest.

Brittany Vargas is a journalist covering medicine, mental health, and wellness.