The Effect of SARS-CoV-2 Vaccination on HIV Viral Load in Patients Under Bictegravir/Tenofovir Alafenamide/Emtricitabine Therapy: A Retrospective Observational Study

<b>Background:</b> The aim of our study is to evaluate the impact of SARS-CoV-2 vaccination on HIV viremia in patients treated under bictegravir-based therapy. <b>Methods:</b> We conducted a retrospective observational study in a tertiary hospital, analyzing data from 152 patients treated with BIC/TAF/FTC between 2020 and 2022. Patients were divided into two groups: "vaccinated" (110/152) and "unvaccinated" (42/152) against SARS-CoV-2. The outcomes considered were the presence of "blips" (detectable viremia ≥ 20 copies/mL), "rebound" (viremia ≥ 50 copies/mL), and virological failures. <b>Results:</b> A lower incidence of blips in the "vaccinated" group compared to the "unvaccinated" group (9.1% vs. 28.6%, <i>p</i> = 0.002), and a reduced risk of blips in the vaccinated group (OR 3.8, 95% CI 1.4-9.8) were noticed. The rebound rate was lower in the vaccinated group compared to non-vaccinated, with a statistically significant difference (respectively, 2.7% vs. 11.9%, <i>p</i> = 0.037). <b>Conclusions:</b> our data suggest that SARS-CoV-2 vaccination may stimulate an immune response that enhances CD4+ and CD8+ cell function, contributing to a reduction in the number of blips and maintaining good viro-immunological control in patients with HIV, supporting the importance of vaccination in this population.