Vaccines against COVID-19 show protection for patients on maintenance dialysis
Compared with unvaccinated patients on maintenance dialysis, those with one to two vaccines against COVID-19 showed better immunity to infection and severe illness.
Further, investigators found vaccine effectiveness did not vary among age groups, mode of dialysis or vaccine type.
“Multiple studies have demonstrated a weaker antibody response to COVID-19 vaccination in the maintenance dialysis population than in the general population,” Matthew Oliver, MD, MHS, a staff nephrologist at Sunnybrook Health Sciences Centre and an associate professor and the division head of nephrology at the University of Toronto in Canada, told Healio. “This population [of patients on maintenance dialysis] in the early phases of the pandemic had high hospitalization rates (60%) and mortality rates (25%) from COVID-19. Vaccination was therefore prioritized by government and strongly encouraged in this population, but it was not clear if the vaccination would adequately protect patients from infection or severe outcomes resulting from infection.”
In a retrospective cohort study, Oliver and colleagues examined 13,759 patients receiving maintenance dialysis in Ontario, Canada between Dec. 21, 2020, and June 30, 2021, to determine vaccine effectiveness. Researchers used provincial health administrative data to identify records of vaccines, COVID-19 infection and related severe outcomes, such as hospitalization or death, among the cohort.
While adjusting for baseline characteristics, background community infection rates and censoring for non-COVID death, recovered kidney function, transfer out of province, solid organ transplant and withdrawal from dialysis, researchers used a time-varying cause-specific Cox proportional hazards model to show receipts of one and two doses of COVID-19 vaccines.
Overall, 17% of the cohort was unvaccinated and 83% received at least one dose of the vaccine by June 30, 2021. A total of 8,455 patients received the Pfizer-BioNTech vaccine, whereas 2,901 patients received the Moderna vaccine.
Analyses revealed that patients who received two or more mRNA vaccines were 69% and 83% less likely to be infected with COVID-19 or experience severe COVID-19, respectively. Throughout the study, researchers observed 663 COVID-19 infections with 323 hospitalizations and 94 deaths.
Vaccinations among the cohort correlated with declined infection risk, hospitalizations and death. While patients who received one vaccine were 41% less likely to become infected with COVID-19 compared with nonvaccinated patients, those with two vaccinations were 69% less likely to catch the virus. Similarly, those with at least one vaccination were 46% less likely to develop severe COVID-19 compared with nonvaccinated patients, and those with two vaccinations were 83% less likely.
“It was not surprising that the vaccine effectiveness was lower than the general population, but it was surprising the protection against severe outcomes remained so high,” Oliver told Healio. “I think this is reassuring for dialysis patients who were concerned the vaccine may not have worked as well for them.”
Perspective
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Early in the COVID-19 pandemic, dialysis patients were at high risk of infection and complications with this new virus. Kidney disease was a risk factor for acquiring infection, and among dialysis patients who were infected, two-thirds required hospitalization and one in four died within 30 days of infection. For dialysis patients in this pandemic, COVID-19 was feared to be the leading cause of death. Hope ran high that a safe and effective vaccine would save thousands of lives.
Several vaccines were rapidly developed and proved safe and effective in the general population. However, dialysis patients were excluded from most of the studies examining safety and efficacy of these vaccines, so as people around the globe rolled up their sleeves for COVID vaccination, dialysis patients and their care teams did not know if these injections would protect them from infection, complications or death.
To answer this question, a team of researchers from Ontario, Canada examined the rates of hospitalization and death among 13,759 patients receiving maintenance dialysis in the period between Dec. 21, 2020, and June 30, 2021. Their results, published in February 2022, showed that two doses of vaccine reduced the rate of laboratory-confirmed infection by 69% and reduced the rate of severe complications including death by 83% compared with unvaccinated dialysis patients. The authors conclude that COVID-19 vaccines are effective in the maintenance dialysis population to prevent both SARS CoV-2 infection and severe outcomes.
The study was well done, and clearly shows the benefits of COVID-19 vaccination for people treated with maintenance dialysis. The authors point out several limitations to interpreting these data. First, the study was conducted before the delta or omicron variants of COVID-19 were widespread in the population. Variant data were not studied in their dialysis patients, the alpha variant was responsible for most cases in the community and the delta variant was responsible for less than 10% of cases. Second, the study preceded the use of third doses of mRNA vaccine and the appearance of the omicron variant in the community.
What is the take-home message? These maintenance patients from Ontario were well protected by COVID-19 vaccines – as demonstrated by many fewer infections, complications and death after they were immunized. This high level of protection was seen in the face of the original alpha variant of infection in the community. Would the protection have been as good for other virus variants, like delta or omicron? We need additional studies to answer that question, but the effectiveness of the vaccines in the general population suggests the answer is probably yes. The vaccines work and save lives.
Were these findings a surprise? If not a great surprise, these findings surely are encouraging, and they answer a question previously unknown about dialysis patients. Even though many dialysis patients may be immune-suppressed, and some may not develop antibodies to virus as robustly as healthy people do, the study shows how effectively dialysis patients are protected by the vaccines.
How do these findings affect clinical practice? For patients or staff who may have reservations about the vaccines, this study should assure them that the vaccines work, are safe and should be used. Compared with unvaccinated dialysis patients, two doses of vaccine reduce death by 85%. This finding makes COVID vaccination among the most effective treatments of any kind for maintenance dialysis patients. While we need to see future studies examining the newer COVID variants, including delta and omicron, these findings should convince all dialysis patients and staff of the life-saving power of COVID immunization and boosters.
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