The following is a summary of “Humoral Immunogenicity of mRNA-1345 RSV Vaccine in Older Adults,” published in the June 2024 issue of Infectious Disease by Goswami, et al.

Researchers conducted a retrospective study to analyze the humoral immunogenicity results from the ConquerRSV trial, in which the mRNA-1345 vaccine had previously shown efficacy for adults ≥60 years old against RSV disease.

They conducted a phase 2/3 trial, randomly assigning adults (≥60 years) to either the mRNA-1345 50-µg vaccine encoding prefusion F (preF) glycoprotein (n=17,793) or a placebo (n=17,748). The RSV-A and RSV-B neutralizing antibody (nAb) and preF binding antibody (bAb) levels were measured at baseline and on day 29 post-vaccination in a per-protocol immunogenicity subset ([PPIS]; mRNA-1345, n=1515; placebo, n=333).

The results showed an 8.4-fold increase in day 29 nAb geometric mean titers (GMTs) against RSV-A and a 5.1-fold increase against RSV-B from baseline. Seroresponses (4-fold rise from baseline) were 74.2% for RSV-A and 56.5% for RSV-B in the mRNA-1345 groups. Participants who met seroresponse criteria had lower baseline GMTs than those who did not. At day 29, mRNA-1345 induced preF bAbs similar to nAbs. Day 29 antibody responses across demographic and risk subgroups were consistent with the overall PPIS.

Investigators found that the mRNA-1345 vaccine can boost immune responses against RSV in older adults, including high-risk groups, which aligns with its prior success in preventing RSV illness.

Source: academic.oup.com/jid/advance-article/doi/10.1093/infdis/jiae316/7695859