High uptake of RSV vaccine and monoclonal antibody reported

High uptake of RSV vaccine and monoclonal antibody reported | Image Credit: © MargJohnsonVA - © MargJohnsonVA - stock.adobe.com.

High uptake has been observed for the respiratory syncytial virus prefusion F protein–based (RSVpreF) vaccine during pregnancy and infant monoclonal antibody (nirsevimab), according to a recent study published in JAMA Network Open.¹

Up to 2% of US infants aged under 6 months are hospitalized with respiratory syncytial virus (RSV) each year, making it the leading cause of hospitalization among this population. A prenatal vaccine and an infant monoclonal antibody received FDA approval in 2023 to protect young infants from infection.

The RSVpreF vaccine protects infants in utero through maternal-fetal antibody transfer after administration in mothers, while nirsevimab may be given to infants aged under 8 months who were not exposed to the RSVpreF vaccine. With a half-life of 2 months, nirsevimab can only be administered once to cover a full RSV season.²

“It is crucial to understand the uptake and outcomes of the newly approved pharmacologic interventions against infant RSV to effectively plan public health initiatives,” wrote investigators.¹ Therefore, the study was conducted to evaluate the RSVpreF vaccine and nirsevimab uptake among eligible patients.

Deliveries at the University of California, San Francisco (UCSF) between October 15, 2023, and April 15, 2024, were included in the analysis. Eligibility criteria included being at 32- to 36-weeks’ gestation during the period of avilability for the RSVpreF vaccine, defined as October 15, 2023, to January 31, 2024.

Exclusion criteria included delivering before 32-weeks’ gestation and not receiving prenatal care at USCF. Vaccination records were obtained from the California Department of Public Health, California Immunization Registry.

Administration of the RSVpreF vaccine during pregnancy, any COVID-19 vaccine prior to pregnancy, and the influenza vaccine and tetanus-diphtheria-pertussis (Tdap) vaccine during pregnancy were considered vaccines of interest. Records were also assessed for administration of nirsevimab during infants’ birth hospitalization.

Medical records were assessed for baseline characteristics, including age at delivery, race and ethnicity, parity, language preference, and primary insurance payer. Medical conditions such as asthma, chronic hypertension, cardiovascular disease, other pulmonary disease, diabetes, obesity, multiple gestation, and assisted reproductive technology use.

There were 647 patients aged a mean 34.6 years included in the final analysis. Of participants, 54.9% were nulliparous, 86.2% privately insured, 26.9% Asian, 8% Black, 18.2% Hispanic, 38.6% White, 4.9% 2 or more races, and 21.8% other or unknown race.

RSVpreF vaccine administration during pregnancy was reported in 64% of patients at a mean gestational age of 33.9 years. Vaccination within 14 days of delivery was reported by 4.6% of patients and not receiving the vaccine during pregnancy by 36%. Two infants were stillborn, leaving 261 eligible for nirsevimab.

Infants eligible for nirsevimab were born at an earlier mean gestational age and were more likely to be submitted to the neonatal intensive care unit than their noneligible counterparts. Preterm birth, preterm premature rupture of membranes, and pregnancy-induced hypertension were also more common in parents of these infants.

Nirsevimab was administered in 70.1% of eligible infants prior to hospital discharge. Administration also occurred in 40.4% of infants whose parents did not receive the RSVpreF or any standard prenatal vaccines during pregnancy, alongside 34% who did not receive the hepatitis B vaccine, 31% erythromycin eye ointment, and 0% intramuscular vitamin K.

RSV coverage remained above 80% for all months except October 2023, which was the first month of availability for both the RSVpreF vaccine and nirsevimab. Older birthing age, nulliparity, private insurance, and non-Hispanic ethnicity were associated with increased RSVpreF vaccine uptake, with adjusted odds ratios of (aORs) of 1.09, 1.84, and 2.19, respectively.

Patients with a prior COVID-19, influenza, or Tdap vaccination were also more likely to receive the RSVpreF vaccine. Reduced odds were reported in those with an English language preference, Black race, other or unknown race, and multiple gestation, with aORs of 0.24, 0.30, and 0.48, and 0.27, respectively.

These results indicated high uptake of the RSVpreF vaccine and nirsevimab among eligible patients. Investigators concluded “an RSV prevention strategy that included both prenatal vaccination and infant monoclonal antibody administration had high uptake and reassuring perinatal outcomes.”

References

1. Blauvelt CA, Zeme M, Natarajan A, et al. Respiratory syncytial virus vaccine and nirsevimab uptake among pregnant people and their neonates. JAMA Netw Open. 2025;8(2):e2460735. doi:10.1001/jamanetworkopen.2024.60735
2. Griffin MP, Yuan Y, Takas T, et al; Nirsevimab Study Group. Single-dose nirsevimab for prevention of RSV in preterm infants. N Engl J Med. 2020;383(5):415-425. doi:10.1056/NEJMoa1913556