A study today in JAMA Network Open from the University of California, San Francisco (UCSF), shows a high uptake of respiratory syncytial virus (RSV) vaccine and the RSV-preventing monoclonal antibody nirsevimab among pregnant women seen during the 2023-24 season, the first RSV season the vaccine and drug were available.
A second study, also published today in the same journal, looked at patients seen at the Beth Israel Deaconess Medical Center in Boston and found a lower uptake of maternal RSV vaccine and nirsevimab (Beyfortus) during the same initial season, but more than half of infants studied were protected.
The first retrospective cohort study included 647 eligible pregnant women, with an average age of 34.6 years. Of the 647 patients, 414 (64.0%) received Pfizer's RSV prefusion F protein-based (RSVpreF) vaccine during pregnancy. The vaccine is commercially available as Abrysvo.
Several factors were associated with high maternal uptake of the vaccine, including older age of the mother (adjusted odds ratio [AOR], 1.09; 95% confidence interval [CI], 1.05 to 1.12), and having no prior pregnancies or children (AOR, 1.84; 95% CI, 1.31 to 2.60). Notably, maternal receipt of any COVID-19 vaccine was highly associated with RSV vaccine uptake (AOR, 7.12; 95% CI, 3.91 to 13.70).
Factors associated with lower odds of receiving maternal RSV vaccination included non-English language preference (AOR, 0.24; 95% CI, 0.10 to 0.52) and Black race (AOR, 0.30; 95% CI, 0.16 to 0.57).
The study also looked at nirsevimab use among 261 eligible infants prior to hospital discharge. Nirsevimab was administered to 183 of 261 eligible infants (70.1%). The authors said nirvesimab was accepted even among parents who had declined other routine prenatal or infant vaccines.
"Among those who did not receive RSVpreF or standard prenatal vaccines, 40.4% of their neonates (19 of 47) received nirsevimab; among those who declined infant hepatitis B vaccination, 34.0% of their neonates (17 of 50) received nirsevimab," the authors wrote.
RSV-protective coverage, via either maternal vaccine or infant nirsevimab administration exceeded 80% in all study months, except the first study month, October 2023.
"This study suggests that an RSV prevention strategy that included both prenatal vaccination and infant monoclonal antibody administration had high uptake and reassuring perinatal outcomes," the authors concluded.
In the second study, 20.5% of mothers and 35.0% of infants received RSV immunizations at the Beth Israel Deaconess Medical Center from September 1, 2023, to January 31, 2024.
Among 1,940 live births seen at the hospital, 54.8% of infants received RSV protection, of which 65.5% received protection after birth. The proportion of infants receiving RSV protection increased each month, from 27.1% in September 2023 to 77.7% in January 2024.
At the end of the RSV season, 389 maternal patients (20.5%) had received RSVpreF and 665 infants (35.0%) received nirsevimab.
Differences in maternal vaccine rates across race and ethnicity categories persisted throughout the RSV season; however, race-based disparities in nirsevimab administration decreased.
"Differences in maternal vaccine rates across race and ethnicity categories persisted throughout the RSV season; however, race-based disparities in nirsevimab administration decreased," the authors said. "Disparities in maternal, but not infant, vaccination persisted throughout the study."