Effectiveness and evolution of anti-SARS-CoV-2 spike protein titers after three doses of COVID-19 vaccination in people with HIV

Background: Real-world vaccine effectiveness following the third dose of vaccination against SARS-CoV-2 remains less investigated among people with HIV (PWH). Methods: PWH receiving the third dose of BNT162b2 and mRNA-1273 (either 50- or 100-μg) were enrolled. Participants were followed for 180 days until the fourth dose of COVID-19 vaccination, SARS-CoV-2 infection, seroconversion of anti-nucleocapsid IgG, death, or loss to follow-up. Anti-spike IgG was determined every 1–3 months. Results: Of 1427 participants undergoing the third-dose COVID-19 vaccination, 632 (44.3%) received 100-μg mRNA-1273, 467 (32.8%) 50-μg mRNA-1273, and 328 (23.0%) BNT162b2 vaccine and the respective rate of SARS-CoV-2 infection or seroconversion of anti-nucleocapsid IgG was 246.1, 280.8 and 245.2 per 1000 person-months of follow-up (log-rank test, p = 0.28). Factors associated with achieving anti-S IgG titers >1047 BAU/mL included CD4 count 200 copies/mL (aOR, 0.27; 95% CI, 0.09–0.80), having achieved anti-spike IgG >141 BAU/mL within 3 months after primary vaccination (aOR, 3.69; 95% CI, 2.68–5.07), receiving BNT162b2 vaccine as the third dose (aOR, 0.20; 95% CI, 0.10–0.41; reference, 100-μg mRNA-1273), and having previously received two doses of mRNA vaccine in primary vaccination (aOR, 2.46; 95% CI, 1,75-3.45; reference, no exposure to mRNA vaccine). Conclusions: PWH receiving different types of the third dose of COVID-19 vaccine showed similar vaccine effectiveness against SARS-CoV-2 infection. An additional dose with 100-μg mRNA-1273 could generate a higher antibody response than with 50-μg mRNA-1273 and BNT162b2 vaccine.