Adenovirus type 5 vector-based COVID-19 vaccine does not increase the likelihood of HIV infection

There is a concern about the potential increased risk of acquiring HIV infection after vaccination with adenovirus type 5 (Ad5) vector-based vaccines. We aimed to investigate whether Ad5-nCoV increases the risk of HIV infection.

Between September 2020 and March 2021, a Phase 3 clinical trial was executed to evaluate the efficacy of Ad5-nCoV. This trial, employing a double-blind, randomized, and placebo-controlled design, enrolled 44,247 participants from 66 clinical sites spanning Argentina, Chile, Mexico, Russia, and Pakistan. Participants were allocated randomly in a 1:1 ratio to receive either Ad5-nCoV or a placebo, and their HIV-negative status was assessed by self-report and confirmed by HIV testing on a baseline blood sample at the end of the study. Consequently, individuals initially administered a placebo received one dose of Ad5-nCoV, while those initially given Ad5-nCoV finally received two doses, with an interval of approximately 6-10 months between administrations. The trial design and primary outcomes have been previously reported. This analysis involves a comprehensive assessment of the associations between pre-existing Ad5 neutralizing antibodies, HIV prevalence and incidence before and after vaccination while accounting for demographic variables.

A total of 43,780 participants who had valid HIV baseline testing results were included in this study. Prior to vaccination, there was no discernible difference in HIV prevalence between the placebo group (0·39% of 21,877 participants) and the Ad5-nCoV group (0·38% of 21,893 participants). This similarity persisted when the data were stratified by country, gender, age, and race. Paired analyses assessing HIV incidence were conducted on participants who tested negative for HIV before vaccination, with data collected over a 6-month period post-vaccination. The results revealed notable similarity in HIV incidence across all groups: 0·29% for Group A (Ad5-nCoV group), 0·21% for Group B (Placebo group), 0·27% for group A + D (Ad5-nCoV group and 1 × Placebo+1 × Ad5-nCoV group), 0·1% for Group C (2 × Ad5-nCoV group), and 0·25% for Group A + C + D (participants who received at least one dose of Ad5-nCoV). Testing approximately 100 randomly chosen participants in each country revealed a similar distribution of pre-existing Ad5 neutralizing antibodies (Nab), with the ratio above a titer of 200 ranged from 65·42% to 67·71%. Notably, the heightened presence of pre-existing Ad5 Nab did not result in an increased risk of HIV infection.

The Ad5-nCoV did not increase the short-term risk of HIV infection in this large and diverse sample of the general population, regardless of the presence of pre-existing Ad5 Nab providing valuable insights into the safety of Ad5 vector-based vaccines.

gov, NCT04526990.