About the Study

CTNPT 045 aims to understand the effect of COVID-19 vaccines on immune response in people living with HIV, and whether these vaccines may increase systemic immune activation and chronic inflammation or negatively affect the viral reservoir. Researchers will determine whether these vaccines induce a protective response in people living with HIV, both in the short- and long-term, and whether this response differs in people living with HIV who have suppressed immune function. This study is complimentary to CTN 328, which also focused on COVID-19 vaccines in people living with HIV; CTNPT 045 provides a detailed look at immune responses to vaccines across different arms of the immune system, and effects on HIV reservoirs, while CTN 328 aimed to understand overall vaccine effectiveness in a large population.


People living with HIV may be at an increased risk of complications related to COVID-19. Only a limited number of people living with HIV were included in the initial clinical trials to test the effectiveness of COVID-19 vaccines. This means that we don’t know how the immune systems of people living with HIV will respond to the vaccine, especially in those with diminished immune responses and chronic inflammation. Research in non–COVID-19 vaccines shows that some vaccines may temporarily increase HIV activity, suggesting that vaccination may affect the HIV reservoir. The viral reservoir refers to the collection of immune cells in the body that may be infected with HIV but are not actively producing new viral particles, effectively hiding the virus from the rest of the immune system and contributing to HIV persistence.

Study Approach

This study enrolled 68 people living with HIV and 23 HIV-negative controls in Toronto. The study involved one screening visit, one baseline visit, and 12 follow-up visits. The screening and baseline visits took place before the first vaccine dose. The follow-up visits took place periodically following each of the three vaccine doses, up to 48 weeks after the first dose.

Participants in this study will learn about their antibody levels, what those antibodies mean, and whether they are from natural infection or the vaccine. Participants were given $35 for each visit. Researchers compared the vaccine-induced immune response between participants living with HIV and HIV-negative individuals. They compared how people living with HIV who have differing levels of immune function respond to the vaccine over the study period.


Preliminary analyses for CTNPT 045 were presented at CROI, SMB (Society for Mathematical Biology), and CITF 2023. Neutralizing antibody responses to two doses of the COVID-19 vaccine were lower in people living with HIV compared to the HIV-negative group. However, after the third dose, neutralizing anti–COVID-19 immunity was similar between the groups. From this analysis, the researchers concluded that two doses of vaccine are not enough for an adequate immune response in older people living with HIV (55 years or older). COVID-19 vaccines did not have a negative effect on the viral reservoir, except in people living with HIV with detectable virus in blood.

Eligibility Requirements


Participants living with HIV:

  • Ability to provide signed written informed consent
  • Documented HIV diagnosis for 1+ year
  • Antiretroviral therapy for 1+ year
  • 55 years of age or older
  • Good general health as shown by medical history and screening laboratory tests at the screening visit

Participants without HIV:

  • Ability to provide signed written informed consent
  • Negative HIV test at the screening visit
  • 55 years of age or older
  • Stable clinical status and absence of acute illnesses as shown by medical history and screening laboratory tests at the screening visit

Please contact participating site for more information about eligibility criteria.

Additional Information

If you would like to take part in this study or want more information, please contact the participating site.

Principal Investigators

Here’s who is leading this study.

Can’t find what you’re looking for? Email ctninfo@hivnet.ubc.ca.

Participating Site

Here’s where this study is being conducted.