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

Oliver MJ, Thomas D, Balamchi S, Ip J, Naylor K, Dixon SN, McArthur E, Kwong J, Perl J, Atiquzzaman M, Singer J, Yeung A, Hladunewich M, Yau K, Garg AX, Leis JA, Levin A, Krajden M, and Blake PG. Vaccine Effectiveness Against SARS-CoV-2 Infection and Severe Outcomes in the Maintenance Dialysis Population in Ontario, Canada. JASN March 2022, ASN.2021091262; DOI:

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

A CITF-funded study – led by Drs. Matthew Oliver from the University of Toronto and Peter Blake from Western University – looked at the effectiveness of mRNA vaccines among 13,759 individuals receiving maintenance dialysis. It determined that one dose of vaccine reduced the risk of COVID-19 infection by 41% and of severe outcomes by 46% compared to unvaccinated patients. Two doses of vaccine were significantly more effective, reducing the risk of infection by 69% and severe outcomes by 83%. The study, published in the Journal of the American Society of Nephrology, confirms that COVID-19 vaccination is protective in this high-risk population, although less so than when compared with general population.

Key points:

  • Although the beneficial effect of one dose of vaccine was relatively modest, two doses of either the Pfizer (N=8455 administered, 74% of participants) or Moderna (N=2901 administered, 26% of participants) mRNA vaccine reduced the risk of SARS-CoV-2 infection by 69% and severe outcomes by 83% among those receiving maintenance dialysis.
  • Among those dialysis patients infected with SARS-CoV-2, the risk of hospitalization in the unvaccinated group was 52% and the mortality rate was 16%. By contrast, the risk of hospitalization among those who had received two doses of vaccine was 30% and the mortality rate was 10%.
  • The importance of the second dose was highlighted by the fact that infection rates of 63% were observed following one dose, as opposed to 35% after two doses.
  • Among the non-COVID-19 related deaths during the period of the study, 20% were observed in unvaccinated individuals, 15% were seen in those with one dose, and only 3% in those with two doses of mRNA vaccine.
  • Unvaccinated patients were more likely to be younger, Black, and had a slightly higher comorbidity index.
  • Individuals were at higher risk for SARS-CoV-2 infection if they were from a racialized community, were on dialysis for a shorter time, lived in a long-term care facility, or resided in a region with a higher community rate of infection.

The participants were recruited between December 21, 2020, and June 30, 2021. None of the participants were on acute dialysis, nor did they test positive for a SARS-CoV-2 infection via RT-PCR before recruitment. Among the participants, 2,403 were unvaccinated and 11,356 had received at least one dose by June 30, 2021. The median time between the first and second dose was 36 days.