New results highlight the need for immunosuppressed patients to remain cautious
Preliminary results from the first UK study investigating how well Covid-19 vaccines work in kidney transplant patients suggest that transplant patients have a weaker antibody response to both the Pfizer/BioNTech and Oxford/AstraZeneca vaccines than healthy individuals.
With this week’s Government announcements that most lockdown restrictions will be lifted from Monday 19 July, many kidney patients are concerned about the risks they face.
In the UK we have seen a fast rollout and a good uptake of the Covid-19 vaccines. But although the vaccines have been thoroughly tested in clinical trials, these trials did not include kidney patients.
We know that kidney patients are more likely to become seriously ill if they catch Covid-19 and we also know that many previous vaccines are not as effective in some patients who are immunosuppressed.
A team of researchers from Imperial College London have published a preprint of the study results, which includes some of the participants of the OCTAVE trial. The preprint focuses on patients who have had a kidney transplant and their immune response to either the Pfizer/BioNTech or the Oxford/AstraZeneca vaccines
A preprint is an academic paper that has been shared publicly but has not yet been published in a journal (which means it has not been subjected to ‘peer review’ — the process where independent scientists assess the quality of the work).
The OCTAVE trial
The OCTAVE trial is a study funded by the Medical Research Council involving teams from Imperial College London, Leeds Teaching Hospitals NHS Trust and the Universities of Glasgow, Birmingham, Oxford and Liverpool, to investigate how well the Covid-19 vaccines work in a wide range of clinically vulnerable patients, including patients with cancer, arthritis and kidney disease.
How did they measure the immune response?
The virus that causes Covid-19 is covered in proteins that it uses to enter our cells. These are called spike proteins. Although the two vaccines (Pfizer/BioNTech and Oxford/AstraZeneca) work differently, they both stimulate the body to produce antibodies – proteins that latch onto viruses and tell the body to destroy them – against these spike proteins.
Antibodies are the first line of defence the vaccine provides if you encounter the virus, but the vaccines also stimulate immune cells called T cells – white blood cells which also work to protect us from diseases.
The team took blood samples from 920 kidney transplant patients after they had been given two doses of either the Pfizer/BioNTech or the Oxford/AstraZeneca vaccine and measured the levels of antibodies against the spike protein of the Covid-19 virus. They also measured the T-cell responses to the Covid-19 virus in 109 patients.
What did they find?
The team found that, overall, 62% of the kidney transplant patients had antibodies against Covid-19 around four weeks after their second dose of vaccine.
Of the patients who had not previously had Covid-19, 66% of patients who were given the Pfizer/BioNTech vaccine developed Covid-19 antibodies in their blood, compared with 44% in patients who received the Oxford/AstraZeneca vaccine. The levels of Covid-19 antibodies were also higher in patients who received the Pfizer/BioNTech vaccine and developed a response.
Patients who were vaccinated in the first year after their kidney transplant were less likely to develop antibodies to Covid-19. The more immunosuppressants people were taking, the less likely they were to develop antibodies.
The team found that T-cell responses to both vaccines were significantly reduced, with only 26% of patients showing a response.
What do these results mean for kidney transplant patients?
The results of this study suggest that kidney transplant patients show a stronger antibody response to the Pfizer/BioNTech vaccine than the Oxford/AstraZeneca vaccine. But overall, transplant patients showed a weaker antibody response to both vaccines than healthy individuals.
The results also suggest that, if possible, patients should be vaccinated before they start immunosuppressive treatments.
The study does not report on whether the vaccine prevented infection in patients, which is the most important measure of how well vaccines work. Although this study shows that kidney transplant patients have a weaker immune response to the Covid-19 vaccines, the vaccines do still offer some protection. Recent data from NHS Blood and Transplant show that of approximately 39,000 transplant recipients who have received both vaccine doses, less than 1% contracted Covid-19 two weeks or more after their second vaccine dose. Of these, 8% died within 28 days of a positive Covid-19 test (compared with 40% in patients who had not been vaccinated ).
We know this is not good enough and we are working closely with the experts to understand the best ways to protect kidney patients.
How we are working to protect kidney patients
- The work complements a study that we are helping to fund to determine how well Covid-19 vaccines work in patients who receive their haemodialysis treatment in hospital.
- In parallel, we are also jointly funding a clinical trial called PROTECT-V, testing a potential treatment to prevent Covid-19 infection. If successful, this could provide an additional layer of protection to that offered by the vaccines.
There is still time for decisive action by the Government
“The evidence is rapidly stacking up that that some kidney patients remain at high risk from Covid-19,” said Dr Aisling McMahon, executive director of research at Kidney Research UK. “More evidence will soon emerge but now is the window of opportunity. There is still time for decisive action by the Government to implement a safety strategy for vulnerable individuals and mitigate the risks they will continue to face once lockdown is eased.
“In the meantime it is vital that kidney transplant patients continue to take their immunosuppressants as prescribed, to prevent their kidneys from being rejected – and take up the vaccine if they haven’t already as this does offer a level of protection. Talk to your renal team if you have concerns.”
Find out more
Visit our information page for more details about the vaccines and staying safe.