RSV immunisation: Maternal versus direct infant immunisation

Presented by

Prof. Simon Drysdale , University of Oxford, UK

Conference

ESCMID Vaccines 2025

Multiple strategies are available to prevent RSV infections in infants, including monoclonal antibodies and vaccines. Prof. Simon Drysdale (University of Oxford, UK) reviewed the latest evidence on RSV immunisation in infants and pregnant women [1].

A recent meta-analysis of 32 real-world studies in infants aged 0-12 months showed that nirsevimab was associated with lower odds of RSV-related hospitalisation, ICU admission, and lower respiratory tract infections (LRTI) [2]. These findings were confirmed in Chilean real-world data (145,087 immunised infants), showing the effectiveness of 76·41% against RSV-related LRTI hospitalisations and 84.94% against RSV-related ICU admissions [3]. Another approved antibody is clesrovimab (not yet EMA-approved), with topline data reporting 90.9% efficacy against RSV-associated LRTI [4].

What about vaccines for RSV? The maternal RSVpreF vaccine evaluated in the phase 3 MATISSE (NCT04424316) trial demonstrated effectiveness of 69.4% against infant medically attended LRTI within 180 days after birth [5]. Real-world data from Argentina confirmed the effectiveness of 71.3% against RSV-associated infant hospitalisation up to age 6 months [6]. Regarding direct infant vaccination, promising results have been reported with live attenuated vaccines, though other platforms such as mRNA have been discontinued [1].

“We now have two long-acting monoclonal antibodies that are approved,” said Prof. Drysdale, “with others in phase 2 or 3 clinical trials not too far away. Live attenuated vaccines are very promising in infants; however, other vaccine platforms seem to be further off [1].”

Drysdale S. Protecting the next generation: RSV vaccination for children & pregnant women. 6^th ESCMID Vaccines, 10–13 September 2025, Lisbon, Portugal.
Sumsuzzman D, et al. Lancet Child Adolesc Health. 2025;9(6):393-403.
Torres JP, et al. Lancet Infect Dis. 2025:S1473-3099(25)00233-6.
Moulia DL, et al. MMWR Morb Mortal Wkly Rep. 2025;74(32):508-514.
Kampmann B, et al. N Engl J Med. 2023;388(16):1451-1464.
Marc GP, et al. Lancet Infect Dis. 2025;25(9):1044-1054.

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