Viral-suppressed PLHIV may not need third dose of COVID-19 vaccine

The researchers concluded that in most cases, people with HIV with a low viral load and high CD4 count do not need a third dose of vaccine, although age, other chronic health conditions, and the vaccination schedule may affect recommendations for additional doses. They also note that a low CD4 count in the past does not appear to affect the response to the vaccine. But since only two study participants had current CD4 counts below 250, more research is needed on vaccine responses in this group.

Canadian researchers reported that people with HIV with well-controlled viral loads receiving antiretroviral treatment have similar antibody levels to HIV-negative people after two doses of SARS-CoV-2 vaccine, and in most cases they will not need a third dose. However, they found that people who received two doses of Oxford / Astra Zeneca vaccine had lower antibody levels after two doses compared to people who received other vaccines. Antibody levels were also lower in the elderly and people with multiple medical conditions.

Health authorities in several countries, including the United States, have recommended that people with HIV with low CD4 counts receive a third dose of the vaccine to improve the immune response to SARS-CoV-2. But there is little information on the immune responses to the standard course of SARS-CoV-2 vaccination in people with HIV to base a recommendation on, and few people with HIV have been included in clinical trials of Pfizer or Moderna vaccines.

To better understand the immune response to SARS-CoV-2 vaccination in people with HIV, Canadian researchers led by Professor Zabrina Bramme of Simon Fraser University in British Columbia recruited 100 PLHIV through three HIV clinics in Vancouver. The HIV-negative control group included 24 people under the age of 65, 39 people over the age of 65, and 89 health workers who had already taken part in another study. They took blood samples before vaccination, where it was possible, one month after the first dose of vaccine, and one month after the second dose.

The median age of people with HIV was 54 years, 88% were men, 69% were white, and chronic diseases were rare among the study participants. All people with HIV received antiretroviral therapy and their last viral load was below 50 copies/ml. The participants had a median CD4 count of 710, and the median of the lowest CD4 count ever was 280.

The HIV-negative control group was dominated by women (67%), less likely they were white (51%) than the HIV-positive group and more likely they received the Pfizer or Moderna mRNA vaccine than people with HIV (97%) … against 83%. 8% of PLHIV received two doses of Oxford/AstraZeneca vaccine, and 7% received one dose of Oxford/AstraZeneca vaccine and one dose of mRNA from Pfizer or Moderna vaccines.

The use of different vaccines for the first and second doses was common in Canada because a second dose using the mRNA vaccine was recommended to anyone who received the Oxford/AstraZeneca vaccine following reports of rare thrombotic events associated with it.

After the first dose of the vaccine, people with HIV had slightly lower antibody levels (-0.4 log lower, p = 0.0001), but after the second dose, the antibody levels in both people with HIV and controls increased by 2 log, and the difference in antibody levels between people with HIV and the control group decreased to -0.1 log (p = 0.04).

Multivariate analysis showed that after the second dose, HIV was not associated with lower antibody levels. Instead, lower antibody levels have been associated with more underlying chronic diseases, receiving two doses of Oxford/AstraZeneca vaccine, or every ten years of extra age.

There was no correlation between the last CD4 count or the lowest CD4 count and antibody levels after the second dose.

Looking at the ACE2 substitution (blocking the interaction between the virus and the ACE2 receptor), the activity was similar in people with HIV and the control group after the second dose. Again, multivariate analyzes showed that older age, more chronic conditions, or two doses of Oxfor/ AstraZeneca vaccine were associated with lower potency.

Receiving two doses of Oxford/AstraZeneca vaccine was associated with significantly greater loss of replacement activity than older age or chronic conditions.

On all counts, HIV was associated with impaired response after one dose of vaccine, but not after two ones. This indicates that people with HIV have a slightly less consistent response to vaccination after one dose, underlining the importance for people with HIV to receive both doses of vaccine at the recommended intervals.

Those who had antibodies to SARS-CoV-2 prior to vaccination had significantly higher antibody levels than those who had no antibodies after a single dose of the vaccine. The second dose of the vaccine did not significantly increase antibody levels in this group. They also showed very strong displacement activity after one dose of the vaccine and maintained significantly higher levels of displacement activity after the second dose than those without a history of COVID-19.