Background: The incidence of non-invasive and invasive Group B Streptococcus (GBS) disease has increased in adults over the last 40 years, particularly in those aged ≥65 years and/or with chronic health conditions.
Methods: Participants aged 55 to 75 years received three doses of 50µg or 125µg GBS-AlpN vaccine containing four alpha-like protein antigens (Alp1N, Alp2/3N, RibN and AlpCN) or placebo (NCT05782179).
Results: Overall, 60 healthy and 30 participants with obesity and/or type 2 diabetes (O/D) were randomized. The median age was 65. Solicited local and systemic AEs (mainly mild, Grade 1/2) were reported for 53 healthy and 26 O/D participants in any 7-day post vaccination period. During any 28-day post vaccination period, no related severe AEs (Grade 3) were reported. Seven unrelated SAEs were reported (three in the placebo group and four in the active groups). Overall, 43 healthy and 22 O/D participants reported ≥1 unsolicited AE during any 28-day post vaccination period. On Day 57 all participants who received GBS-AlpN seroconverted for all four AlpNs except for two healthy participants in the 50µg group (one for Alp1N and one for RibN) and one O/D participant in the 50µg group (for AlpCN and RibN). On Day 197 all participants seroconverted except one healthy in the 50µg group and one O/D in the 125µg group, both for RibN.
Conclusions: A 3-dose schedule of GBS-AlpN in healthy and O/D older adults showed an acceptable safety profile. A robust immune response against all four AlpNs was induced after the second dose.