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  • A study compared the immune response to COVID-19 vaccination in 100 HIV-positive and 152 HIV-negative people
  • After two vaccine doses, participants had high levels of protective antibodies regardless of HIV status
  • Factors such as older age and other health conditions were more likely to affect antibody levels than HIV

Initial studies of COVID-19 vaccines did not provide detailed analyses of the response to vaccination in HIV-positive people. To address this shortcoming, doctors and scientists around the world are conducting studies.

A team of Canadian researchers at the BC Centre for Excellence in HIV/AIDS in Vancouver and at universities in British Columbia, Ontario and Quebec cooperated in a study to compare the effects of COVID-19 vaccines in people with and without HIV. In this study, participants were generally healthy and those who were HIV positive were all on HIV treatment (ART), 95% of whom had a suppressed viral load (less than 50 copies/mL).

Overall, the study’s results were very promising. High levels of antibodies that attacked SARS-CoV-2 (the virus that causes COVID-19) were found in both HIV-positive and HIV-negative participants one month after receiving the second dose of COVID-19 vaccines. Further research is planned or ongoing to better understand how long the immune response to COVID-19 vaccination persists.

Study details

Researchers recruited 100 HIV-positive people and 152 HIV-negative people from the metro Vancouver area. A majority (59%) of the HIV-negative people were healthcare workers. The average profile of HIV-positive participants was as follows:

  • age – 54 years
  • 88% men, 12% women
  • major ethno-racial groups: White – 69%; Asian – 10%; Black – 5%
  • all were taking ART
  • 95% had a viral load less than 50 copies/mL; the remainder had a viral load between 71 and 162 copies (prior to the study, participants had a history of suppressed viral loads)
  • CD4 count – 700 cells/mm3
  • lowest-ever (nadir) CD4+ count – 300 cells/mm3

Note that these figures are averages and some people had lower or higher CD4+ cell counts.

Most of the HIV-negative participants were women (67%). On average, they were around 47 years old.

Most of the study participants, both HIV positive and HIV negative, had no chronic health conditions. Of those with chronic health conditions, the two most common were high blood pressure and asthma.


All participants were vaccinated between December 2020 and August 2021.

Most participants received an mRNA vaccine, distributed as follows:

First dose

  • HIV-positive people – 83% received an mRNA vaccine
  • HIV-negative people – 97% received an mRNA vaccine

Second dose

  • HIV-positive people – 92% received an mRNA vaccine
  • HIV-negative people – 99% received an mRNA vaccine

This difference in the distribution of mRNA vaccines between the two study populations arose because a large proportion of the control (HIV-negative) group were healthcare personnel who were prioritized for vaccination. They received mRNA vaccines because at that time the AstraZeneca vaccine was not yet approved in Canada. After Canada approved the AstraZeneca vaccine, a minority of participants received it. However, over the course of the study, the use of this vaccine declined in Canada. Therefore, some people who initially received this vaccine for their first dose were subsequently given an mRNA vaccine for their second dose. In this study, 8% of HIV-positive people received both doses of the AstraZeneca vaccine vs. less than 1% of HIV-negative people.


After one dose of any COVID-19 vaccine, the levels of antibodies that recognized SARS-CoV-2 were significantly lower in HIV-positive people than in HIV-negative people.

However, after participants received their second dose of vaccine, researchers stated that levels of protective antibodies rose “substantially” in all but two people:

  • an HIV-positive person in their 60s who had what the researchers called a “chronic blood disorder” (details were withheld to protect the privacy of this person)
  • an HIV-negative person over the age of 80 who had three other chronic health conditions

In the vast majority of participants, after two doses of vaccine, the levels of antibodies that recognize SARS-CoV-2 were comparable between participants with and without HIV.

Taking many issues into account, the researchers found that participants who had low levels of protective antibodies were likely to have one or more of the following characteristics:

  • older age
  • chronic health conditions
  • received two doses of the AstraZeneca vaccine

Having a history of a low CD4+ cell count prior to initiation of ART was not associated with a poor immune response to vaccination among HIV-positive people.

About age

When it came to age, the researchers did not identify a specific age "cutoff" after which vaccine immune responses were notably poorer. Rather, vaccine responses were generally weaker with increasing age. In other words, the average vaccine response of a 60 year old was not as strong as it was in a 50 year old.

Bear in mind

According to the researchers, HIV-positive people who are “receiving stable ART, who had suppressed viral loads and who have CD4+ T cell counts in the healthy range generally mount robust [antibody-based] immune responses to COVID-19 vaccines.”

The researchers noted that factors such as older age, having a higher number of chronic health conditions and what type of vaccines a person got were all more important than HIV in determining the strength of a person’s immune response to the COVID-19 vaccines. It is important to note that 99% of participants with HIV in the study mounted an immune response after receiving two COVID-19 vaccine doses. 

In their initial release of data, the researchers did not directly assess the ability of the vaccine-induced antibodies to attack SARS-CoV-2. However, this data will be released soon. The antibodies they studied are very likely the ones needed to stop SARS-CoV-2 from causing infection and complications.

The present study is a good first step in exploring the immunological effects of COVID-19 vaccines in people with HIV. Additional research is necessary to explore the effect of these vaccines in HIV-positive people in Canada who:

  • have low CD4+ cell counts
  • are not taking ART
  • are children or adolescents
  • are Indigenous

Note that the present study focused on antibody levels. COVID-19 vaccines also help train T-cells to attack SARS-CoV-2. This provides an additional level of protection from the virus. The researchers plan to study T-cell responses and other immunological and virological issues in the future. They plan to continue to follow the study participants over time to see how long immune responses incited by vaccination last.


We thank Professor Zabrina Brumme, PhD, at Simon Fraser University and the BC Centre for Excellence in HIV/AIDS, for her helpful comments and expert review.

—Sean R. Hosein


COVID-19 resources

British Columbia Centre for Excellence in HIV/AIDS

Frequently asked questions about vaccines for the prevention of COVID-19CATIE

Encouraging results from the Pfizer-BioNTech COVID-19 vaccine in HIV-positive peopleCATIE News

AstraZeneca COVID-19 vaccine stimulates immunity to SARS-CoV-2 in HIV-positive peopleCATIE News


Brumme Z L, Mwimanzi F, Lapointe HR, et al. Humoral immune responses to COVID-19 vaccination in people living with HIV on suppressive antiretroviral therapy. Preprint. 4 October 2021. https://medrxiv.org/cgi/content/short/2021.10.03.21264320v1