RSV Prevention in Pregnancy: Options and Challenges

The development of prevention strategies against respiratory syncytial virus (RSV) in pregnancy and infancy is a significant milestone; however, challenges remain, such as overcoming vaccine hesitancy, determining the relative benefits of maternal vs infant vaccination, and ensuring the equitable availability of RSV prevention options, researchers reported in Obstetrics & Gynecology.

The investigators reviewed recent recommendations for RSV prevention during pregnancy and addressed potential challenges for RSV vaccination.¹

In 2023, the US Food and Drug Administration (FDA) approved the Abrysvo vaccine for RSV in pregnancy between 32 and 36 weeks of gestation, which followed the approval of nirsevimab against RSV for infants. In September 2023, the Centers for Disease Control and Prevention’s (CDC) Advisory Committee on Immunization Practices recommended RSV vaccination for all pregnant patients at 32 to 36 weeks of gestation anticipated to deliver during the RSV season if they were not planning to use nirsevimab for their infants.

The CDC’s Advisory Committee on Immunization Practices has recommended use of nirsevimab in infants younger than 8 months born before or during RSV season as well as infants and children aged 8 to 19 months with a risk of severe RSV disease. In October 2023, the CDC also issued a Health Alert Network regarding the shortage of nirsevimab, recommending prioritization of the drug for infants with the highest risk for severe RSV disease.

The FDA approved the Abrysvo RSV vaccine based on a phase 3 randomized controlled trial of healthy patients aged 49 years or younger with an uncomplicated, singleton pregnancy and no known increased risk of pregnancy complications and a gestational age of 24 to 36 weeks.² Efficacy of the vaccine was 81.8% against medically attended severe RSV-associated lower respiratory tract illness in infants within 90 days after birth and 69.4% within 180 days after birth. However, efficacy for medically attended nonsevere RSV-associated lower respiratory tract disease during the initial 90 days of life did not achieve the prespecified criterion.

To date, clinical RSV vaccine trials have focused on uncomplicated, low-risk, singleton pregnancies, with the Abrysvo trial excluding patients who had an increased risk of pregnancy complications, noted the researchers. Thus, no data are available for RSV vaccination in pregnant patients with more complex or high-risk pregnancies. Assessing long-term outcomes in exposed offspring also is limited by follow-up length in trials, and there is a lack of evidence on the safety and efficacy of vaccines during pregnancy and lactation to prevent disease in the infant.

Challenges in RSV vaccination include vaccine hesitancy in pregnant patients and the relatively short half-life of maternally derived RSV-specific antibodies in the infant. Studies are needed to further determine whether coadministration of RSV vaccinations in pregnancy with the Tdap vaccine decreases the Tdap antibody response.

“We hope that ongoing studies will focus on the role of maternal vaccination compared with infant vaccination, whether there is a role, and under which circumstances,” the authors stated. “In addition, long-term safety data after maternal vaccination are needed.”

Steps also should be taken to ensure that disparities in health care are not further increased and that all patients are offered RSV vaccination in pregnancy or monoclonal antibody in the early neonatal period before discharge, the authors noted. “Pfizer has reported maternal vaccine pricing of about $295.49. Nirsevimab is priced at about $495,50, and neonatal vaccination will likely result in hospitals having to absorb the cost into deliveries unless covered under the CDC’s Vaccines for Children program, which applies to only 12% of hospitals,” the authors added.

This article originally appeared on Pulmonology Advisor