Many dialysis patients remain vulnerable to Omicron

As the government in England relax the latest set of COVID-19 restrictions, new data from researchers at the Francis Crick Institute raise concern of the impact on dialysis patients. Published as a research letter in The Lancet, the results show that, even after third doses of vaccination, a significant fraction of patients receiving in-hospital dialysis treatment appear to remain at risk from the Omicron variant.

The ongoing NAOMI study, funded by a coalition of kidney charities including Kidney Research UK, the National Kidney Federation, Kidney Wales, the PKD Charity and several Kidney Patient Associations, showed that the variant continues to pose a risk to kidney disease patients on dialysis despite them having received a second or even third dose of the vaccine. 

Researchers showed that after three vaccine doses, patients had lower levels of neutralising antibodies- antibodies that are able to block entry of the virus into cells- against Omicron when compared to Delta. Additionally, patients who received just two doses of the vaccine were also less likely to show a detectable antibody response to Omicron than Delta.  With two doses of the Oxford/AstraZeneca vaccine, antibody levels were too low to detect for both variants in most patients. This is important because neutralising antibodies are a crucial component of the protection afforded by vaccination.

Patients who had received the Oxford/AstraZeneca vaccine for their first two doses were less likely to have detectable levels of antibodies able to neutralise Omicron. Only 48% of this group had detectable neutralising antibody levels after 3 doses, compared to 72% of patients who had the Pfizer-BioNTech mRNA vaccine for their first two doses.

The majority of kidney patients on dialysis are currently only eligible for two primary doses of the vaccine as well as a booster. The results of this latest study reveal that kidney patients on in-hospital dialysis remain vulnerable to the latest dominant variant, and also suggest that they may require a fourth dose of the Covid-19 vaccine to ensure adequate protection from Omicron. 

The research team measured the levels of neutralising antibodies against the Omicron and Delta variants in 98 patients who travel to hospital for dialysis sessions. All patients studied had received at least their second or even third dose of the Covid-19 vaccine. 

Rupert Beale, head of the Crick’s Cell Biology of Infection Laboratory, said: “New variants will continue to arise as the pandemic evolves, and for vulnerable patients, it’s especially important to assess the specific risks. We’ve shown that Omicron has raised the threshold for effective protection and that patients undergoing dialysis shouldn’t assume protection after three doses. Our study suggests four doses of vaccine would benefit dialysis patients.”

Edward Carr, postdoctoral clinical fellow in the Crick’s Cell Biology of Infection Laboratory, said: “Patients in need of kidney dialysis treatment are making regular visits to hospital and are also more vulnerable to severe COVID-19 infection. Some of these patients are considered to be immunocompromised because of the medication they’re taking or their comorbidities. Currently, just these patients - and not all dialysis patients - are automatically offered a fourth vaccine dose.  

“Our data supports fourth doses for all kidney dialysis patients to maximise levels of protection in this group.” 

Researchers are continuing to monitor both the impact of new variants and the number of vaccines needed to offer sufficient protection to those in the most vulnerable categories. The results of this most recent study add to the existing evidence for the Joint Committee on Vaccination and Immunisation to consider recommending a fourth dose for kidney patients on dialysis. 

Dr Aisling McMahon, Executive director of Research, Innovation and Policy at Kidney Research UK, said: “As the pandemic continues, it is extremely important that we continue to monitor how well the vaccines are protecting kidney patients. These findings clearly show that many patients on dialysis are still vulnerable to Covid-19 infection, particularly the Omicron variant, even after three vaccine doses. We believe this study provides strong evidence that patients who travel to hospital for dialysis should receive a fourth vaccine dose to ensure they have the best protection possible.”