Respiratory Syncytial Virus Prophylaxis for Premature Infants: Insights
from a Multicenter Out-of-Season Study
Abstract
Objective: To elucidate the impact of lack of Palivizumab
administration during off-season RSV periods on the RSV-related
hospitalization among 29-34 weeks of gestational age (wGA) preterm
infants. We utilized the summer of 2021 off-season RSV surge during the
COVID19 pandemic. Methods: This multi-center retrospective
observational study was conducted in 11 medical centers across Israel.
We included infants > 1 year-old hospitalized with RSV
infection between November 2017-August 2021. Patients were categorized
into an in-season admissions group (November-March) and off-season
admissions group (April-October). The primary outcome was the proportion
of RSV hospitalizations among 29-34wGA infants in relation to total RSV
admissions during the same season. Secondary outcomes included clinical
severity parameters. Results A total of 3,296 infants were
admitted during the RSV season, and 1,044 during the off-season. The
proportion of 29-34wGA preemies was significantly higher in the
off-season group compared to the in-season group (7% vs 2.1%,
p<0.001). In the off-season group, we observed a significantly
higher proportion of Jewish individuals (80.1% vs. 59.2%, p=0.001) and
higher socioeconomic status (55.1% vs. 45.1%, p<0.001)
compared to the in-season group. In the multivariable
logistic-regression model, off-season hospitalization odds for 29-34 wGA
preemies were significantly higher (2.6-fold, 95% CI:1.8-3.9,
p<0.001) compared to in-season, irrespective of demographic
covariates. Similar clinical severity parameters was observed between
the groups. Conclusions Our results revealed a significantly
higher proportion of infants born at 29-34 wGA among those hospitalized
during off-season periods compared to in-season periods. These findings
highlight the importance of including 29-34 wGA infants into future RSV
immunoprophylaxis recommendations.