RSV vaccine plus flu or COVID-19 shots safe, feasible in older adults

Coadministration of mRNA-1345, a respiratory syncytial virus (RSV) vaccine, with an influenza (flu) or a COVID-19 vaccine in older adults exhibits good tolerability and has an acceptable reactogenicity profile, according to a US study presented at ESCMID Global Congress 2024.

“All geometric mean titre ratios (GMR) noninferiority objectives were met in adults ≥50 years [of age], suggesting that mRNA-1345 can be coadministered with influenza and mRNA SARS-CoV-2 vaccines in this population,” said lead author J Goswami from Moderna, Inc, Cambridge, US.

Goswami and colleagues conducted a phase III, multipart, double-blind study to assess the feasibility of coadministration of mRNA-1345 (50-µg) with licensed quadrivalent seasonal influenza (Afluria Quadrivalent; 60-µg) or mRNA SARS-CoV-2 vaccines (Spikevax Bivalent [ancestral+omicron BA.1]; 50-µg) in older adults.

A total of 3,304 older adults received vaccination, of which 1,623 participated in part A and 1,681 in part B. In part A, participants were randomized to receive either mRNA-1345 plus Afluria Quadrivalent, mRNA-1345 plus placebo, or Afluria Quadrivalent plus placebo. In part B, participants randomly received mRNA-1345 plus Spikevax Bivalent, mRNA-1345 plus placebo, or Spikevax Bivalent plus placebo. The primary endpoint in both parts was safety.

In addition, the main immunogenicity endpoints were as follows: noninferiority of antibody responses of coadministered mRNA-1345 plus Afluria Quadrivalent against RSV-A and influenza strains (part A) and noninferiority of coadministered mRNA-1345 plus Spikevax Bivalent against RSV-A and SARS-CoV-2 strains (ancestral and omicron strains; part B) to comparators at day 29. A secondary objective in both parts was the noninferiority of immune responses against RSV-B.

Parts A and B of the study showed that coadministration of RSV vaccine with either a flu or a COVID-19 vaccine in older adults was “generally well-tolerated”, with an acceptable reactogenicity profile. [ESCMID Global 2024, abstract O0878]

In part A, GMRs on day 29 exhibited noninferiority of antibody responses of coadministered mRNA-1345 plus flu vaccine against RSV-A (GMR, 0.81, 95 percent confidence interval [CI], 0.67‒0.97), but not seroresponse rate (SRR) differences.

Additionally, GMR for all strains of influenza (A/H1N1: 0.89, 95 percent CI, 0.77‒1.03; A/H3N2: 0.97, 95 percent CI, 0.86‒1.09; B/Victoria: 0.91, 95 percent CI, 0.81‒1.02; B/Yamagata: 0.93, 95 percent CI, 0.82‒1.05) and RSV-B (0.85, 95 percent CI, 0.73‒1.00) were all >0.667. Day 29 SRR difference for RSV-B was ‒14.3 percent (95 percent CI, ‒21.5 to ‒6.9).

In part B, all immunogenicity endpoints were met, with the coadministered vaccines showing noninferiority to comparators for RSV-A (GMR, 0.80, 95 percent CI, 0.70‒0.90) and SARS-CoV-2 strains (ancestral: GMR, 0.96, 95 percent CI, 0.87‒1.06; omicron: GMR, 1.01, 95 percent CI, 0.89‒1.14) based on day 29 GMRs and SRR differences. Coadministered vaccines also achieved noninferiority against RSV-B based on GMR only (0.89, 95 percent CI, 0.79‒1.00).

“Coadministration of RSV with flu or COVID vaccines will reduce healthcare visits and potentially increase vaccination rates,” Goswami said.