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. 2017 Feb;36(2):160-167.
doi: 10.1097/INF.0000000000001377.

Burden of Severe Respiratory Syncytial Virus Disease Among 33-35 Weeks' Gestational Age Infants Born During Multiple Respiratory Syncytial Virus Seasons

Free PMC article

Burden of Severe Respiratory Syncytial Virus Disease Among 33-35 Weeks' Gestational Age Infants Born During Multiple Respiratory Syncytial Virus Seasons

Evan J Anderson et al. Pediatr Infect Dis J. .
Free PMC article


Background: Moderate-late preterm infants, 33-35 weeks' gestational age (wGA), are at increased risk for respiratory syncytial virus hospitalization (RSVH). The objective of this study is to quantify the burden of RSVH in moderate-late preterm infants.

Methods: A pooled analysis was conducted on RSVH from 7 prospective, observational studies in the Northern Hemisphere from 2000 to 2014. Infants' 33-35 wGA without comorbidity born during the respiratory syncytial virus season who did not receive respiratory syncytial virus immunoprophylaxis were enrolled. Data for the first confirmed RSVH during the season (+1 month) were analyzed. Incidence and hospitalization rate per 100 patient-seasons, intensive care unit admission and length of stay (LOS), oxygen support, mechanical ventilation and overall hospital LOS were assessed.

Results: The pooled analysis comprised 7,820 infants; 267 experienced a confirmed RSVH at a median age of 8.4 weeks. The crude pooled RSVH incidence rate was 3.41% and the rate per 100 patient-seasons was 4.52. Median hospital LOS was 5.7 days. A total of 22.2% of infants required intensive care unit admission for a median LOS of 8.3 days. A total of 70.4% received supplemental oxygen support for a median of 4.9 days, and 12.7% required mechanical ventilation for a median of 4.8 days.

Conclusions: The burden of RSVH in moderate-late, 33-35 weeks' wGA preterm infants without comorbidities born during the viral season in Northern Hemisphere countries is substantial. Severe cases required prolonged and invasive supportive therapy.

Conflict of interest statement

Funding support for this pooled database analysis was provided by AbbVie. E.J.A., X.C.-E., M.B., M.L., M.S.-P. and B.P. have received research funding and/or compensation as advisor/lecturer from AbbVie. E.J.A. has received research funding from MedImmune. B.R.-G. and J.F., working for Strategen, have previously received payment from AbbVie for work on various projects. E.R., P.V. and F.C. are former employees of AbbVie and may hold AbbVie stock or stock options. G.N. is an employee of AbbVie and may hold AbbVie stock or stock options. The authors have no conflicts of interest to disclose.


PRISMA of systematic review process. Stage 1 review: 2 reviewers assessed citations for inclusion/exclusion based on the title and abstract. Stage 2 review: 2 reviewers assessed each citation for inclusion/exclusion based on the full text. Reasons for exclusion were categorized as follows: population (eg, outside 33–35 weeks’ gestational age range), intervention (eg, study including >15% of infants receiving prophylaxis), study type (eg, retrospective) or new study available (ie, 2 studies available from the same country whereupon the newer one would be included). For both stages, if a consensus could not be reached, a third experienced reviewer made the decision. PRISMA indicates Preferred Reporting Items for Systematic Reviews and Meta-Analyses.
Diagram of derivation of analytical dataset.
RSVH distribution in 33–35 wGA preterm infants during the RSV season (+1 month). Peak month shown in parentheses.

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