The research by London’s Francis Crick Institute found that in patients who had not been previously infected with the Covid-19 virus (coronavirus) those who had received the ‘Pfizer-BioNTech’ mRNA vaccine had six-times higher levels of neutralising antibodies (proteins that defend a human cell from infectious particles such as viruses by neutralising any effect they have biologically) against the more contagious Covid-19 ‘Delta’ variant, compared to people vaccinated with the ‘Oxford-AstraZeneca’ vaccine. 

The levels induced by the mRNA vaccine were comparable to those seen in healthy controls after both vaccine doses.  In patients who had already had Covid-19 prior to vaccination, both vaccines induced detectable levels of neutralising antibodies. 

These findings suggest that patients who have not been infected with the Covid-19 coronavirus previously and received the Oxford-AstraZeneca vaccine, would likely benefit from an early third dose of an alternative mRNA vaccine.

Levels of antibodies alone do not predict vaccine effectiveness and researchers are confident that for most people, two doses of either vaccine will still protect against severe disease or death. 

Findings can inform future research strategies

Edward Carr, postdoctoral clinical fellow in the Francis Crick’s Cell Biology of Infection Laboratory, says: “Unfortunately, the risk from Covid-19 has been much greater for dialysis patients as we’ve seen high rates of admissions and deaths in this group. 

“The level of neutralising antibody to Delta made by haemodialysis patients, who have not had a prior Covid-19 infection and received the Oxford-AstraZeneca vaccine, might not be enough to prevent infection with Delta. 

“Importantly, we’ve found that this group (without prior infection) respond well to mRNA vaccines and we can use this information to inform future vaccination strategies.”

Dr Aisling McMahon, executive director of research, innovation and policy at Kidney Research UK, said, “This is extremely timely research. We already know that many kidney patients respond less well to vaccines than the general population. 

“The good news is that both these vaccine technologies are protecting people from serious illness. However, many dialysis patients still need to travel to hospital several times a week for life-saving treatment and so remain more at risk of catching Covid-19.

“These findings clearly indicate that dialysis patients (who have not previously had Covid-19) are unlikely to be adequately protected from the delta variant if they received the AZ vaccine. 

“We believe that this study provides strong evidence to support a third dose of an mRNA vaccine as standard treatment as soon as possible for all immunocompromised patients who potentially remain at risk. 

Rupert Beale, head of the Cell Biology of Infection Laboratory, said: “The vaccination programme in the UK has been a huge success, but the pandemic isn’t over. As most people enjoy increased freedom, many immunocompromised patients remain vulnerable. Our data suggest that delivering a third dose of vaccine will be necessary to protect some patient groups.”

What the research team did

The research team examined blood samples from 178 patients receiving haemodialysis treatment. The study includes patients from across the UK and will, in time, report on over 1,000 haemodialysis patients. They used robust high throughput viral neutralisation assays (laboratory tests), developed at the Crick, to test the ability of antibodies to block entry of the virus into cells, so called ‘neutralising antibodies’, against different variants of SARS-CoV-2 (the virus which causes Covid-19) including the Delta variant.

Find out more

To find out more about Covid-19 in kidney patients visit our Covid-19 Hub.

The Kidney Charities Together group strongly recommend that precautions are still taken to remain COVID safe. Read their response to the new research.