Two doses of either the Pfizer-BioNTech COVID-19 vaccine or the Oxford AstraZeneca alternative provide equal and significant protection against severe disease in patients on hemodialysis who have contracted SARS-CoV-2 infection, results of a multicenter observational study indicate.
Following two doses of either vaccine, the risk of hospital admission was 75% lower among vaccinated patients while the risk of death was 88% lower, compared with those who remained unvaccinated.
No difference was seen between the two vaccine types in terms of outcome severity, and there was no loss of protection in patients over the age of 65 or with increasing time since vaccination, the authors add. The need for oxygen and ventilation was also halved among those who had received two shots, compared with those who had not.
“The coronavirus disease 2019 (COVID-19) pandemic has had a devastating effect on the CKD (chronic kidney disease) community, particularly for individuals receiving maintenance dialysis,” Matthew Oliver, MD, University of Toronto, and Peter Blake, MD, Western University, London, Ont., write in an editorial published with the study.
“Overall, [this and other studies] show that COVID-19 vaccination in the maintenance dialysis population provides moderate protection against acquiring SARS-CoV-2 infection but is highly protective against severe outcomes,” they conclude.
The study was published in the June issue of the Clinical Journal of the American Society of Nephrology.
Severe outcomes observed less in patients who tested positive
The cohort included 1,323 patients on hemodialysis who tested positive on PCR testing to SARS-CoV-2 during a surveillance interval between December 2020 and September 2021, report, Damien Ashby, MD, Hammersmith Hospital, London, and colleagues report.
Among those who tested positive, 79% had not been vaccinated, 7% tested positive after their first dose of either vaccine, and 14% tested positive at least 10 days beyond their second dose.
The course of illness was mild in 61% of patients in that they did not require hospital admission, investigators note. Oxygen support was required by 29% of those who tested positive, and 13% died before 28 days, they added. Among those who died within 28 days of testing positive, 90% of the deaths were deemed to be caused by the virus itself.
“Compared with unvaccinated patients, severe COVID-19 outcomes were observed less than half as often in patients testing positive for SARS-Co-V-2 at least 10 days after the second dose,” Dr. Ashby and colleagues emphasize.
“And the protection from severe illness associated with vaccination was most obvious in patients over 65 years, in whom severe COVID-19 outcomes were reduced at least as much after vaccination as in their younger peers,” they add. Following vaccination with the Pfizer-BioNTech vaccine, antibody levels in patients on dialysis were comparable with those of healthy controls.
In contrast, this was not the case for the Oxford AstraZeneca vaccine where neutralizing titers in patients who received the vaccine were less effective against most variants. Despite its ability to produce comparable immunogenicity, the Oxford AstraZeneca vaccine was clearly associated with clinical protection against severe illness, the authors stress.
They also note that their results are relevant to vaccine uptake in the dialysis population where vaccine hesitancy remains a problem. “This study may, therefore, be useful in reducing vaccine hesitancy, which has resulted in low uptake in some countries (for example, Australia, where almost a quarter of patients on dialysis declined),” Dr. Ashby and colleagues point out.
Although significant vulnerability in the dialysis population remains, “this population has much to gain from vaccination, regardless of age or vaccine type,” the authors underscore.