The Centers for Disease Control and Prevention’s (CDC) Advisory Committee on Immunization Practices (ACIP) has adopted the recommendation for maternal vaccination for respiratory syncytial virus (RSV) of pregnant individuals 32 to 36 weeks gestation, using seasonal administration, in order to prevent RSV lower respiratory tract infection in infants.1
The recommendation was made by the ACIP at a virtual meeting on Friday, September 22, 2023,1 which followed on the heels of Food and Drug Administration (FDA) approval of Pfizer’s RSV vaccine Abrysvo™ for use in pregnant individuals on August 21, 2023.2 Abrysvo was first approved by the FDA in May 2023 for individuals older than 60 years of age and was formally recommended for use in this population by ACIP on June 21, 2023.3
The ACIP also voted to approve Abrysvo for the Vaccines for Children Program, thus making it available to pregnant people under 19 years of age.1
RSV is currently the leading cause of hospitalization among infants in the US.4 The ACIP’s recent recommendation of maternal RSV vaccination means that there are now 2 treatment options available for the prevention of RSV in infants; nirsevimab, which has been shown to reduce RSV-related hospitalizations and visits by approximately 80% in infants1, was recommended by ACIP on August 3, 2023, for all infants younger than 8 months born during or entering their first RSV season. It was also recommended for infants and children aged 8 through 19 months who are at increased risk for severe RSV disease and are entering their second RSV season.5
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Most infants will likely only need protection from either the maternal RSV vaccine or infant immunization, but not both.
“Most infants will likely only need protection from either the maternal RSV vaccine or infant immunization, but not both,” stated a CDC press release.1
Window to Vaccinate Pregnant Individuals
In explaining the ACIP recommendation for the FDA-approved maternal vaccination window of 32 to 36 weeks gestation, Katherine E. Fleming-Dutra, MD, co-lead of the CDC’s RSV Vaccines Pediatric/Maternal Work Group noted that “there is less opportunity for serious adverse events, including preterm birth/delivery,” with this interval vs the wider 24- to 36-week gestation vaccination period used in Pfizer’s phase 3 trial of Abrysvo (ClinicalTrials.gov Identifier: NCT04424316). Notably, the phase 3 trial data show a slightly lower rate of preterm births among US mothers vaccinated during the 32- to 36-week gestation period vs US mothers in the corresponding placebo cohort (4% vs 4.4%, respectively), Dr Fleming-Dutra reported.6
Seasonal Vaccine Administration
The CDC’s RSV Vaccines Pediatric/Maternal Work Group recommended seasonal vaccine administration to mothers during September through January in most of the US. For infants born outside of the vaccination window, nirsevimab is recommended. Additionally, it is recommended that infants born within 2 weeks of maternal RSV vaccination receive nirsevimab due to inadequate transfer of maternal antibodies to protect the infant.1
According to Jefferson Jones, MD, a presenter at the ACIP meeting who is also a co-lead RSV Vaccines Pediatric/Maternal Work Group, “Most work group members felt that pregnant people should be aware that both maternal vaccination and nirsevimab are options when deciding whether to be vaccinated,” and that shared clinical decision making should be used when deciding on the use of both the maternal RSV vaccine and nirsevimab in the infant.7
Dr Jones further noted that proposed clinical considerations for the maternal RSV vaccine and nirsevimab antibody protection may begin to decrease after 3 or more months following maternal vaccination.7 However, at this time, existing evidence does not suggest that revaccination is needed.3
