Most infants admitted to the ICU with RSV do not have an underlying medical condition, but RSV remains a top cause of hospitalization in the first year of life.

Most infants admitted to an intensive care (ICU) or high acuity unit with RSV lower respiratory tract infections during the peak 2022 season were young, healthy, and born at term, Natasha Halasa, MD, MPH, and colleagues report in JAMA Network Open.

“This surveillance registry of infants with critical RSV illness highlights that RSV causes significant morbidity in previously healthy term infants as well as those born prematurely and those with underlying conditions. Thus, prevention strategies are needed for all infants,” the authors conclude.

Worldwide, RSV is the leading cause of respiratory-related hospitalization in young children, and in the United States, RSV is the leading cause of hospitalization in children in their first year of life.

Study Conducted During 2022 “Tripledemic”

In a cross-sectional study, Dr. Halasa and colleagues reviewed prospective surveillance data in the RSV Pediatric Intensive Care (RSV-PIC) registry from 39 pediatric hospitals in 27 states. The researchers included the first 15 to 20 consecutive eligible infants aged less than 1 year of age from each site for a target sample size of 600. In this sample, the median age was 2.6 months; 361 (60.2%) were male, 169 (28.9%) were premature births, and 487 (81.2%) had no underlying medical conditions.

The study included participants admitted for 24 or more hours to an ICU or a high acuity unit between October 17, 2022 and December 16, 2022 due to laboratory-confirmed RSV infection. This period coincided with the height of the fall 2022 “tripledemic” of increased hospitalizations for COVID-19, influenza, and RSV.

The researchers found that the primary reasons for admission included lower respiratory tract infection in 594 (99.0%) infants and apnea or bradycardia in 77 (12.8%).

Overall, 143 (23.8%) patients received invasive mechanical ventilation, for a median of 6.0 days. Among non-intubated infants, 243 (40.5%) received high-flow nasal cannula, 150 (25.0%) received bilevel positive airway pressure, and 52 (8.7%) received continuous positive airway pressure. The study found an increased risk of intubation for patients aged less than 3 months, those with gestational age less than 37 weeks, and publicly insured infants (Figure).

Four (0.7%) infants received extracorporeal membrane oxygenation, and 2 died. The median hospital stay for survivors was 5 days.

Documentation of receipt of the monoclonal antibody palivizumab was available for only 2 of 17 infants eligible for the drug due to having a gestational age of less than 29 weeks, “highlighting potential barriers to administration and emphasizing the need to ensure that all eligible patients receive it in a timely manner,” the authors write.

Protecting Patients & Mitigating Stress on the Healthcare System

“During RSV season, especially if circulation is high, RSV could be associated with severe illness in young infants,” Dr. Halasa cautions. “Also, if we have another RSV peak, this may increase stress on ICUs.”

Most infants admitted to the ICU with severe RSV did not have an underlying medical condition, she notes. “Our data support the need for RSV preventative interventions targeting all infants, to reduce the burden of severe RSV illness. They include nirsevimab, the long-acting RSV-neutralizing monoclonal antibody, and maternal RSV vaccination.”

Further, the implementation of community mitigation measures slowed RSV circulation. That circulation increased following the loosening of such measures, according to Dr. Halasa.

“With new monoclonal antibodies, and maternal RSV vaccination products coming down the pipeline, it’s important to document which infants are being admitted with severe RSV illness and to characterize their illnesses and outcomes. If these new prevention measures are implemented, it will be important to see if they reduce severe RSV. We hope our findings will aid in the design of future RSV prophylactic and maternal RSV vaccine effectiveness and usage studies and recommendations.”