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November 10, 2023
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Burden of RSV in pregnant people lower than older adults, children but still significant

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Key takeaways:

  • The proportion of respiratory infections testing positive for RSV among pregnant people ranged from 0.9% to 10.7%.
  • Two studies showed RSV hospitalization rates of 2.4 and 3 per 1,000 person-years.

Respiratory syncytial virus incidence rates among pregnant people are lower than those seen in older adults and young children, although researchers say rates are still significant and warrant consideration in vaccine policy decisions.

“The study was initiated in response to the successful outcomes of the RESCEU project on the respiratory syncytial virus (RSV) disease burden in children and older adults and the promising prospects of RSV vaccines for various populations,” Sebastien Kenmoe, PhD, a research fellow at the Centre for Global Health in University of Edinburgh’s Usher Institute, told Healio.

Pregnant woman in hospital_135759782
A systematic review showed that the proportion of respiratory infections testing positive for RSV among pregnant people ranged from 0.9% to 10.7%, which researchers said is low compared with older adults and young children but is still significant. Image: Adobe Stock.

“We were motivated by the need to understand the impact of RSV in pregnant individuals, especially with the emergence of maternal RSV vaccines aimed at protecting only the fetus and infant ... [and] to provide comprehensive data to aid vaccine policy decisions, especially considering the vulnerability of pregnant women and the potential impact on both neonatal and maternal health,” he said.

Kenmoe and colleagues conducted a systematic review following PRISMA 2020 guidelines using Medline, Embase, Global Health, Web of Science and Global Index Medicus, as well as some unpublished data.

Data from all pregnant people with respiratory infections who had samples tested for RSV were included. The researchers then used a random-effects meta-analysis to generate overall proportions and rate estimates across studies. In total, 11 studies including 8,126 pregnant people recruited between 2010 and 2022 were identified and included.

Overall, the study showed that the proportion of pregnant people with respiratory infections who tested positive for RSV ranged from 0.9% to 10.7%, with a meta-estimate of 3.4% (95% CI, 1.9-54), and the pooled incidence rate of RSV infection episodes among pregnant people was 26 (95% CI, 15.8-36.2) per 1,000 person-years.

Data on RSV hospitalization rates were reported in two studies and showed rates of 2.4 and 3 per 1,000 person-years, whereas five studies reporting on RSV-associated deaths among more than 4,000 pregnant people said no deaths were reported.

The researchers added that studies comparing RSV-positive and RSV-negative pregnant people found no difference in odds of miscarriage, stillbirth, low birth weight and/or small for gestational age, although RSV-positive pregnant people had higher odds of preterm delivery (OR = 3.6; 95% CI, 1.3-10.3).

Kenmoe said that the implications of these findings in terms of maternal RSV vaccination efforts are “multifaceted.”

“Firstly, they highlight the potential benefits of RSV vaccination for pregnant women, not only to protect their infants but also to reduce the risk of preterm delivery associated with RSV infection,” he said. “Secondly, the data suggest that the burden of RSV in pregnant women, while not as high as in older adults and children, is still significant and warrants consideration in vaccine policy decisions.”

Kenmoe added that as countries evaluate the inclusion of RSV vaccines in maternal vaccination programs, these findings could provide “crucial insights” into the disease burden and could inform strategies to optimize the health outcomes of both mothers and their babies.

“Health care providers should recognize the risk of RSV infection during pregnancy, which can lead to preterm delivery,” Kenmore said. “Given the substantial benefits of maternal vaccines observed with influenza and COVID-19, RSV vaccination could similarly protect against preterm delivery risks and contribute to the overall health of the mother and infant.”

He said that with the availability of maternal RSV vaccines, clinicians have a new tool to potentially reduce this risk.

“It is vital to consider RSV vaccination as part of comprehensive prenatal care, especially given the low incidence of adverse perinatal outcomes,” Kenmore said. “Our study supports the responsible integration of maternal RSV vaccination into public health policy to enhance the protection of both mothers and infants from the consequences of RSV infection.”