Poor durability of the neutralizing response against XBB sublineages after a bivalent mRNA COVID-19 booster dose in persons with HIV

We estimated the dynamics of the neutralizing response against XBB sublineagesand T cell response in persons with HIV (PWH) with previous AIDS and/orCD4 < 200/mm 3 receiving the bivalent original strain/BA.4‐5 booster dose in fall2022. Samples were collected before the shot (Day 0), 15 days, 3, and 6 monthsafter. PWH were stratified by immunization status: hybrid immunity (HI; vaccinationplus COVID‐19) versus nonhybrid immunity (nHI; vaccination only). Fifteen daysafter the booster, 16% and 30% of PWH were nonresponders in terms of anti‐XBB.1.16 or anti‐EG.5.1 nAbs, respectively. Three months after, a significant waningof anti‐XBB.1.16, EG.5.1 and ‐XBB.1 nAbs was observed both in HI and nHI butnAbs in HI were higher than in nHI. Six months after both HI and nHI individualsdisplayed low mean levels of anti‐XBB.1.16 and EG.5.1 nAbs. Regarding T cellresponse, IFN‐γ values were stable over time and similar in HI and nHI. Our datashowed that in PWH, during the prevalent circulation of the XBB.1.16, EG.5.1, andother XBB sublineages, a mRNA bivalent vaccine might not confer broad protectionagainst them. With a view to the 2023/2024 vaccination campaign, the use of themonovalent XBB.1.5 mRNA vaccine should be urgently warranted in PWH toprovide adequate protection.