This is a summary, written by members of the CITF Secretariat, of:

Nault L, Marchitto L, Goyette G, Tremblay-Sher D, Fortin C, Martel-Laferrière V, Trottier B, Richard J, Durand M, Kaufmann D, Finzi A, Tremblay C. Covid-19 vaccine immunogenicity in people living with HIV-1. bioRxiv 2021.08.13.456258. doi :

The results and/or conclusions contained in the research do not necessarily reflect the views of all CITF members.

Few studies have shown that immunocompromised individuals may mount attenuated antibody responses, compared to their otherwise healthy counterparts. A new pre-print, therefore not yet peer-reviewed, by CITF-funded researcher Dr. Andrés Finzi and Dr. Cécile Tremblay, both from the University of Montréal, found that the immunogenicity of a single dose of the Moderna vaccine in people living with HIV depended on their CD4+ T cell count.

In people living with HIV (PLWH), an essential component of the immune system that helps orchestrate both cellular and humoral (antibody-based) immunity (CD4+ T cells) are targeted by the HIV virus. Previous studies have shown that PLWH may mount lower antibody responses to vaccines, contingent on the level of their CD4+ T cell counts. Fortunately, the majority of PLWH who are being treated with well-tolerated antiretroviral drugs tend to achieve immune recovery with normalized CD4+ T cell counts. In this study, researchers examined the immunogenicity of a single dose of Moderna’s vaccine in PLWHIV-1 (people living with HIV-1).

Key points:

  • There were no significant differences between the level of antibodies induced in PLWH compared to healthy controls following one dose of the Moderna vaccine.
  • However, PLWH with lower CD4+ T cell counts (under 250 cells/mm3) mounted significantly lower antibody responses after one dose of the vaccine compared to those with higher CD4+ T cell counts.

These findings highlight the need to consider additional strategies such as booster shots and immune-monitoring for specific populations to ensure adequate protection against COVID-19.