Burden of respiratory syncytial virus-associated acute respiratory infections during pregnancy.

INTRODUCTION With the licensure of maternal RSV vaccines in Europe and USA, data are needed to better characterize the burden of respiratory syncytial virus (RSV)-associated acute respiratory infections (ARI) in pregnancy. This study aims to determine among pregnant individuals the proportion of ARI testing positive for RSV and RSV incidence rate, RSV-associated hospitalizations, deaths, and perinatal outcomes. METHODS We conducted a systematic review following PRISMA 2020 guidelines using five databases (Medline, Embase, Global Health, Web of Science and Global Index Medicus) and included additional unpublished data. Pregnant individuals with respiratory infections who had respiratory samples tested for RSV were included. We used a random-effects meta-analysis to generate overall proportions and rate estimates across studies. RESULTS Eleven studies with pregnant individuals recruited between 2010 and 2022 were identified, most of which recruited pregnant individuals in community, inpatient and outpatient settings. Among 8126 pregnant individuals, the proportion with respiratory infections that tested positive for RSV ranged from 0.9% to 10.7%, with a meta-estimate of 3.4% (95% CI: 1.9; 54). The pooled incidence rate of RSV infection episodes among pregnant individuals was 26.0 (15.8; 36.2) per 1000 person-years. RSV hospitalization rates reported in two studies were 2.4 and 3.0 per 1000 person-years. Of five studies that ascertained RSV-associated deaths among 4708 pregnant individuals, no deaths were reported. Three studies comparing RSV-positive and RSV-negative pregnant individuals found no difference in odds of miscarriage, stillbirth, low birth weight, and small for gestational age. RSV-positive pregnant individuals had higher odds of preterm delivery (odds ratio 3.6 [1.3; 10.3]). CONCLUSION Data on RSV-associated hospitalization incidence rates are limited but available estimates are lower than those reported in older adults and young children. As countries debate whether to include RSV vaccines in maternal vaccination programs, which are primarily intended to protect infants, this information could be useful in shaping vaccine policy decisions.