Supporting equitable booster strategies. One-year real-world immunogenicity data in people with HIV (pwh) receiving different variant-adapted covid-19 vaccines

Objectives: To compare the 12-month immunogenicity of Nuvaxovid XBB.1.5 (protein-based) and Pfizer-BioNTech monovalent mRNA XBB.1.5 boosters in people with HIV (PWH) on stable antiretroviral therapy, assessing humoral and cellular immune responses against ancestral and emerging SARS-CoV-2 variants. Methods Fifty participants with a median age of 58 years (interquartile range, IQR 52, 66), all previously primed with at least four monovalent mRNA doses, received either Nuvaxovid (n = 24) or mRNA vaccine (n = 26), depending on availability. Anti-receptor binding domain (RBD) IgG, neutralizing antibodies (nAbs) against D614G, XBB.1.16, JN.1, LP.8.1, and IFN-γ T-cell activity were measured at baseline (T0), 1 month (T1), and 12 months (T2) post-booster. Results At T1, anti-receptor binding domain (RBD) IgG titers were higher in the mRNA group than in the Nuvaxovid group (6942 vs 4143 BAU/mL; P = 0.01), but nAbs and T-cell responses showed no significant differences. At T2, humoral responses were comparable, with a trend toward higher LP.8.1 nAb titers in Nuvaxovid recipients (P = 0.06). Mixed-model analyses confirmed stronger short-term LP.8.1 nAb responses with mRNA, but slower waning with Nuvaxovid. No consistent differences were observed for other variants. Discussion Overall, mRNA boosters provided a stronger early humoral response, while Nuvaxovid may promote more sustained T-cell immunity. Both maintained robust responses over 12 months, supporting their use in people with HIV (PWH). Given its thermostability and accessibility, Nuvaxovid is a practical alternative when mRNA vaccines are unavailable or contraindicated.