Nearly One-Third of Infant Acute Hospitalizations in 4 Countries Associated With RSV

Nearly a third of hospitalizations for infant acute illness in 4 middle-income countries was found to be associated with respiratory syncytial virus (RSV). Low weight for age and other factors could be good predictors of RSV severity for these infants, according to a study published by The Journal of the Pediatric Infectious Disease Society.

RSV has been found to be a major cause of acute lower respiratory tract infection and hospitalizations in all infants across the globe. Peak RSV incidence could be affected by country income classification, with those in the lower income bracket facing a higher burden in young infants. This study enrolled infants from lower- and upper-middle-income countries to “describe RSV epidemiology, factors associated with illness severity, and anti-RSV IgG serum antibodies among RSV-positive infants, with an overall aim of expanding infant RSV data from outside of high-income counties…”

The researchers collected data from Albania, Jordan, Nicaragua, and the Philippines during 2 study periods in all but the Philippines, where the study took place in a 34-week period. Infants younger than 1 year were scanned prospectively and were eligible if they were admitted for less than 24 hours and had illness onset within 10 days. Infants were not included if their hospital admission was not due to acute illness.

Interviews with parents and medical record reviews were done for all eligible infants. Clinical test results and discharge status was also collected. All infants had respiratory specimens that included nasal and throat swabs tested at laboratories. All of these specimens were tested for RSV with a reverse transcription polymerase chain reaction test.

Any infant hospitalized for RSV was determined to have severe illness, with very severe illness being defined as infants who needed supplemental oxygen or a trip to the intensive care unit (ICU). Vital signs were also obtained from medical records.

There were 3634 infants who were hospitalized during the study period and 1129 (31%) tested positive for RSV. RSV-positive rates were 42% in Albania, 34% in Jordan, 22% in Nicaragua, and 20% in the Philippines. A total of 39% of the infants had RSV-A, 53% had RSV-B, 1% had both RSV A and B, and 7% were undetermined.

The median (IQR) age of children who had RSV was 2.7 (1.4-6.1) months; 53% were younger than 3 months and 59% were young boys. A total of 8% of infants were preterm, 14% had a low birth weight, and 6% had at least 1 parent who reported an underlying condition; however, 80% of the children who had RSV had none of these conditions.

A median (IQR) of 3 (2-4) days’ worth of illness were found in infants before hospitalization, with cough being the most commonly reported symptom (90%). Cough and difficulty breathing were reported in 92% of the infants and fever or feeling hot was reported by parents in 51% of infants.

A total of 27% of infants who had RSV across all 4 countries were admitted to the ICU initially and 32% required the ICU after being hospitalized. Very severe illness was found in 52% of infants. Infants with very severe illness had a median age of 2.0 months compared with 4.3 months in infants with severe illness. The proportion of very severe RSV was higher in infants aged 0 to 2 months compared with infants in other age categories in Albania and Jordan (67% and 79%, respectively). The proportion of very severe RSV in infants aged 0 to 2 months and 3 to 5 months was higher than in infants who were older than 6 months in the Philippines.

Infants with very severe illness were more likely to be younger (adjusted odds ratio [aOR], 4.1; 95% CI, 2.6-6.5 for infants aged 0-2 months compared with 9-11 months), have a low weight for age (aOR, 1.9; 95% CI, 1.2-2.8), have been born via cesarean delivery (aOR, 1.4; 95% CI, 1.0-1.8), and have been in the ICU after birth (aOR, 1.6; 95% CI, 1.0-2.5) compared with those with severe illness.

Thresholds for administration of oxygen therapy and admission to the ICU likely varied by site, which could have influenced the analysis of disease severity. Resources and capacity, including ICU capacity, could vary. Possible bacterial coinfection had incomplete data. Parental report on birth history was relied on rather than objective measures. Enrollment periods may not have captured the full RSV season in either year.

The researchers concluded that the middle-income countries had young infants who were hospitalized with RSV that frequently received ICU care or oxygen therapy and were admitted for an average of 6 days which likely resulted in burden on health care in areas with limited resources.

Reference

Biggs HM, Simões EAF, Khader IA, et al. Respiratory syncytial virus infection among hospitalized infants in four middle-income countries. J Pediatric Infect Dis Soc. Published online June 14, 2023. doi:10.1093/jpids/piad042