High Frequency of Chronic Urticaria Following an Investigational HIV-1 BG505 MD39.3 Trimer mRNA Vaccine in a Phase 1, Randomized, Open-Label Clinical Trial (HVTN 302)

The mRNA platform is under investigation for many vaccines, including HIV-1 vaccines. To evaluate the safety and tolerability of 3 investigational HIV-1 trimer mRNA vaccines. Safety analysis of mRNA vaccination in a phase 1, randomized, open-label trial. (ClinicalTrials.gov: NCT05217641). Ten research sites in the United States. 108 volunteers aged 18 to 55 years without HIV-1. Investigational HIV-1 BG505 MD39.3 trimer mRNA vaccines (gp140 soluble trimer, gp151 membrane-bound trimer, and gp151 CD4KO membrane-bound trimer) at doses of 100 and 250 mcg at 0, 2, and 6 months. Solicited and unsolicited adverse reactions and events reported during the 12 months after the first vaccination. Participants (n = 108) were randomly assigned to 6 vaccine groups. Mild to moderate local and systemic solicited events were common. Eighty participants reported 190 unsolicited adverse events (AEs); 30 were considered to be related to a study product. Most (73%) related AEs were mild, and the rest were moderate. Among related AEs, urticaria was reported by 7 of 108 participants (7% [95% CI, 3% to 13%]), 4 of whom had unresolved, intermittent urticaria at 12 months. In post hoc analyses, demographic characteristics, history of allergy or medication use, and COVID-19 were not associated with urticaria. In a comparison of participants with versus without urticaria, 100% (7 of 7; CI, 65% to 100%) versus 37% (37 of 101; CI, 28% to 46%) reported previous Moderna COVID-19 vaccination, 29% (2 of 7; CI, 8% to 64%) versus 76% (77 of 101; CI, 67% to 84%) reported previous Pfizer-BioNTech COVID-19 vaccination, and 0% (0 of 7; CI, 0% to 35%) versus 5% (5 of 101; CI, 2% to 11%) reported no previous mRNA COVID-19 vaccination. Lack of a placebo group, open-label study, and post hoc evaluation of urticarial risk. Urticarial reactions associated with experimental HIV-1 mRNA vaccines were observed in this trial. Studies to investigate the mechanism and approaches to mitigate these reactions are underway to further advance HIV-1 vaccine research. National Institutes of Health, National Institute of Allergy and Infectious Diseases.