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

Puyat JH, Wilton J, Fowokan A, Janjua NZ, Wong J, Grennan T, Chambers C, Kroch A, Costiniuk CT, Cooper CL, Lauscher D, Strong M, Burchell AN, Anis A, Samji H; COVAXHIV Study Team. COVID-19 vaccine effectiveness by HIV status and history of injection drug use: a test-negative analysis. J Int AIDS Soc. 2023 Oct;26(10):e26178. doi:

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

A CITF-funded study, published in the Journal of the International AIDS Society, found that vaccine effectiveness against SARS-CoV-2 infection may be lower in people living with HIV (PLWH) with a history of injection drug use (IDU). The overall vaccine effectiveness during the first two months after second dose was lower among PLWH with IDU history than PLWH with no IDU history compared to matched HIV-negative individuals with or without history of IDU. This study was led by Dr. Aslam Anis (University of British Columbia).

This study aimed to investigate how both HIV and a history of IDU jointly affect vaccine effectiveness (VE). The comparison groups here included: PLWH with IDU history, PLWH with no IDU history, HIV-negative individuals with IDU history, and HIV-negative individuals without IDU history.

Key findings:

  • The proportion of people with IDU history was much higher among PLWH (41%) than HIV-negative individuals (4%).
  • Overall, VE against SARS-CoV-2 infection during the first two months after second dose was lower among PLWH with IDU history (66%) than PLWH with no IDU history (80%). Immunity waned significantly four to six months after vaccination among PLWH with a history of IDU compared to other groups.
  • In contrast, overall VE against SARS-CoV-2 infection was 92% in the first two months in the matched HIV-negative population with no history of IDU and remained relatively high at four to six months after the second dose.

This study suggests that lower vaccine effectiveness observed among PLWH may be partially attributed to substance use and associated health conditions. People with both HIV and IDU history had the greatest comorbidity burden and neighbourhood income deprivation. The study findings emphasize the need for tailored strategies, including booster dose prioritization for PLWH (with and without IDU history) to enhance COVID-19 vaccine protection.

The study included PLWH and HIV-negative individuals from the BC COVID-19 Cohort (BCC19C), a surveillance platform integrating COVID-19 datasets with a range of administrative and registry datasets. Data from individuals who received an RT-PCR laboratory test for SARS-CoV-2 between December 15, 2020 and November 21, 2021 in British Columbia, Canada were included in analysis. The study included 2,700 PLWH and a matched population of 375,043 HIV-negative individuals, among whom there were 351 and 103,049 SARS-CoV-2 cases, respectively. The study period was chosen to coincide with the vaccine rollout in the general population in BC (first dose became available on December 15, 2020) and ended prior to the emergence of Omicron.