Respiratory syncytial virus (RSV)- and human metapneumovirus (hMPV)-associated lower respiratory tract disease (LRTD) contributes substantially to morbidity and mortality in older adults. IVX-A12 is an investigational combination vaccine comprised of two virus-like particles computationally designed to elicit immune responses against RSV and hMPV. In a Phase I randomized trial, IVX-A12 was well tolerated and elicited RSV- and hMPV-specific neutralizing antibody (nAb) responses in adults 60–75 years of age. In this Phase IIa trial, healthy adults 60–85 years of age, including participants with stable, chronic conditions, were randomized 2:2:1 to receive one intramuscular dose of IVX-A12 (150 μg RSV/150 μg hMPV) with/without MF59® (oil-in-water adjuvant), or placebo (diluent), stratified by age group (60–69/70–85 years). Safety and immunogenicity were assessed through 365 days post-vaccination. Overall, 264 participants received IVX-A12 ( n = 211) or placebo ( n = 53). Solicited adverse reactions were mild-to-moderate in severity and were reported by 57.3% ( n = 59/103), 75.0% ( n = 81/108), and 37.7% ( n = 20/53) of recipients of unadjuvanted IVX-A12, IVX-A12 + MF59®, and placebo, respectively. IVX-A12 induced increases in nAbs against RSV and hMPV. From baseline to Day 28, in IVX-A12 (±MF59®) recipients, nAbs against RSV A and B increased 5–6- and 3–4-fold, respectively, and nAbs against hMPV A and B both increased 2–3-fold. In IVX-A12 recipients, all except hMPV A nAbs remained above baseline levels at Day 365 and were higher than in placebo recipients. Addition of MF59® to IVX-A12 did not boost antibody responses nor increase their duration. Safety and immunogenicity were similar between the stratified age groups. IVX-A12 was well tolerated and induced RSV- and hMPV-specific antibody responses in adults 60–85 years of age. This trial demonstrated the feasibility of an RSV/hMPV combination vaccine. • IVX-A12 was well tolerated and immunogenic in adults 60–85 years of age. • IVX-A12 immune responses against RSV and hMPV remained above baseline past Day 180. • Use of adjuvant did not impact the antibody response or its duration. • Immunogenicity was similar in participants 60–69 (53%) and ≥70 years of age (47%). • Safety results were similar in the 60–69 and ≥70 years age groups.
Davis et al. (Wed,) studied this question.