Speaker
Description
Preexposition prophylaxis (PrEP) was approved for use in the Spanish National Health System in late November 2019. We examined whether PrEP roll-out had an effect on HIV-1 clustering in Spain. For this study, protease-reverse transcriptase sequences from HIV-1 infections diagnosed in 11 Spanish regions in the years before and after PrEP roll-out were analyzed with an approximate maximum likelihood method. No significant change in the proportion of HIV-1 infections grouping in all clusters comprising ≥4 individuals was observed. However, when large clusters (≥30 individuals) were analyzed separately, a statistically significant 36% decrease in HIV-1 infections belonging to them was observed from 2021 to 2022, which was consistent in different very large clusters (≥100 individuals) and regions. In contrast to the overall decline of infections grouping in large clusters, we observed in the post-PrEP period the expansion of 3 moderate-sized (21-28 individuals) clusters, designated B261, B289, and B328, that increased > 6-fold in new diagnoses from 2016-2019 to 2020-2023. All 3 clusters had in common that a majority of infections were diagnosed in the region of Castilla y León. Phylodynamic analyses with the Bayesian skyline plot (BSP) method estimated exponential increases in the number of effective infections mainly in the immediate pre-PrEP period in B261 and B289, and in the early post-PrEP period in B328, with subsequent stabilization. Therefore, although most new diagnoses in the 3 clusters were from 2022 and 2023, they appear to reflect pre-PrEP or early post-PrEP roll-out transmissions. Regarding the 4 very large clusters (≥100 individuals), BSP analyses indicated no apparent change in 2 and exponential decreases in the other 2, during 2019 and 2020 and during 2020, respectively, with subsequent stabilization. These results support the potential usefulness of phylogenetic and phylodynamic analyses for monitoring the efficacy of PrEP and other public health interventions against HIV-1.
