HIV and COVID vaccines: How an unsuppressed viral load reduces the production of antibodies

Swedish researchers have discovered that people living with HIV who had a detectable viral load at the time they received their COVID-19 vaccinations produced fewer antibodies than those with an undetectable viral load. The results of the COVAXID study have been published in the journal AIDS.

For the purpose of the COVAXID study, researchers compared the immune response to the Pfizer vaccine in 79 people living with HIV and a control group of 82 HIV negative individuals.

All participants living with HIV were taking antiretroviral therapy, 80% of which were on integrate inhibitors. In this group 86% had an undetectable viral load (<50 copies/ml) and 14% had a viral load exceeding 50 copies/ml. Forty participants (49%) had a CD4 count below 200 cells/μl. There were no significants differences in demographics between the people living with HIV and the control group.

Participants received two doses of the Pfizer vaccine with a three week interval. Researchers measured the level of IgG antibodies at 21 and 35 days after the second dose to determine the immune response.

Almost all participants (98.7% PLH, 100% control) produced the expected antibodies 35 days after vaccination, apart from one person in the HIV group - a 69-year-old individual with an autoimmune disease, who was not on immunosuppressive treatment.

But the results showed that people living with HIV had significantly lower antibody levels that the control group, with the HIV group recording a median IgG level of 1,613 U/ml versus the control group with 2,192 U/ml. Participants with an active viral load above 50 copies/ml had significantly lower antibody levels however.

This study highlights the need to work with people living with HIV to create an optimised treatment regimen that is both effective and easy to adhere to, so that viral loads can be kept low and vaccinations kept effective.

The team says that this analysis is the first study linking lower COVID-19 vaccination antibody levels to individuals with active viral loads. They also acknowledge that limitations of their study saying that it may be skewed by the “inclusion of individuals with an increased risk for severe COVID-19. Therefore, the study cohort does not reflect our general patient population in terms of age and comorbidities.”