COVID-19 vaccination does not affect viral load or reservoir size in people with HIV, Canadian study finds

The COVID-19 mRNA vaccines do not affect HIV viral load or the HIV viral reservoir, according to the results of a small Canadian study combined with province-wide analyses.

About This Study

“Effects of COVID-19 mRNA vaccination on HIV viremia and reservoir size” was published online on Jan. 15, 2024, in AIDS. The lead author is Maggie C. Duncan of the British Columbia Centre for Excellence in HIV/AIDS in Vancouver, and of the Faculty of Health Sciences at Simon Fraser University in Burnaby, both in Canada.

Key Research Findings

Researchers assessed changes in HIV reservoir size and viral load pre- and post-vaccination against COVID-19 in 62 people living with HIV who received two doses of an mRNA vaccine, spread over as many as 112 days. Five participants acquired COVID-19—four prior to vaccination and one between the two doses. Median participant age was 43 years, 89% of participants were men, and median antiretroviral treatment duration was six years.

Prior to vaccination, 82% of participants had an undetectable HIV viral load (defined as less than 20 copies/mL), and everyone was virally suppressed (defined as a maximum viral load of 110 copies/mL). Among 59 study participants included in the final analysis, undetectable viral load continued in 79% after the first vaccine dose and 85% after the second dose. Maximum viral loads at these two time points were 183 copies/mL and 79 copies/mL, respectively.

The median intact HIV reservoir was 77 copies/million CD4 cells pre-vaccination, 74 copies/million CD4 cells after the first dose, and 65 copies/million CD4 cells one month after the second dose. Results did not differ among participants who had/had not acquired COVID-19, nor by sex or antiretroviral regimen. Defective proviral loads also did not change pre- and post-vaccination.

The researchers also investigated whether the mass COVID-19 vaccination campaign in British Columbia was associated with an increase in the frequency of detectable HIV viral loads in people with HIV.

They found that despite the more than 9 million COVID-19 vaccine doses administered in that province in 2021, the percentage of people with HIV receiving uninterrupted antiretroviral therapy who experienced at least one detectable viral load measurement was essentially identical to that observed in 2019, prior to the pandemic, at 18.5%. This same rate remained consistent in 2022.

Discussion Highlights and Implications for Practice

Study limitations reported included HIV sampling one month after each vaccine dose, potentially missing rapid viremia events that may have resolved quickly. Results may also not apply to people with poorly controlled HIV prior to vaccination, the researchers cautioned.

Combined with results from other research, the study authors concluded that COVID-19 vaccination is safe in people living with HIV.

By Barbara Jungwirth