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New study to investigate how third doses of Covid-19 vaccine protect immunocompromised patients

09 December 2021

We are pleased to support researchers at London’s Imperial College in a study to understand how well third doses of vaccine protect immunocompromised patients against Covid-19.

The study, known as ‘MELODY’, will involve 36,000 immunocompromised patients across the UK, starting with those with kidney and other organ transplants, and then later including patients with cancer and autoimmune diseases.

Since the initial vaccine rollout, the Government’s Joint Committee on Vaccination and Immunisation has recommended that immunocompromised patients should have an mRNA vaccine (either ‘Pfizer/BioNTech’ or ‘Moderna’) for their third dose, regardless of the initial vaccine they received. This advice was updated last week to recommend that immunocompromised patients should also be given a fourth vaccine dose three months after the third dose.

The study will provide vital insights into which patients remain vulnerable to Covid-19 after vaccination. The research is being funded by the Medical Research Council in collaboration with several health charities including Kidney Research UK, Blood Cancer UK, Vasculitis UK, and the Cystic Fibrosis Trust, with support from NHS Digital, NHS Blood and Transplant and the Department of Health and Social care.

It is estimated that approximately 500,000 people in the UK have an immunocompromising condition and research suggests that Covid-19 vaccines may not provide full protection for many of these patients.

Photo by Steven Cornfield on Unsplash

Why this research now?

Early analysis of responses to a third dose of a COVID-19 vaccine in transplant patients in other countries suggests that up to 25% of these patients may remain unprotected.

However, given the variation in the types of vaccines and dosing schedules used in different countries, it is not possible to extrapolate directly from this data for the UK.

In the UK, approximately 60% of transplant patients received the ‘Oxford-AstraZeneca’ vaccine in the initial rollout. This study will provide crucial information as there are currently no data available on responses to third dose vaccines after immunisation with the ‘Oxford-Astrazeneca’ vaccine in immunocompromised patients.

How will the study work?

Researchers will measure whether patients have developed antibodies (proteins that are produced by the body’s immune system to help fight against infection) against the virus that causes COVID-19.

Patients will use a home-based, self-administered rapid test at least 21 days after they receive their third dose of the vaccine. Unlike the commonly used lateral flow rapid antigen tests which detect infection with the Covid-19 virus, patients will be asked to provide a drop of blood from a self-administered thumb or finger prick to detect whether a patient has developed antibodies.

Researchers will also ask participants to complete a questionnaire online, including questions about patient demographics, details of immunosuppressive treatments and patient behaviour which will then be linked to antibody results.

Dr Aisling McMahon, executive director of research, innovation and policy at Kidney Research UK, which co-funded the study, said, “We are thrilled to support this research to identify patients who remain unprotected after three doses of COVID-19 vaccine. While vaccination has demonstrated significant benefits in reducing risk for many patients, this study will investigate the proportion of patients still at risk after their third dose.

“This is the only study we are aware of that will identify this vulnerable group of patients, who remain at increased risk of hospitalisation and mortality. It will allow doctors to suggest alternative protective measures for some people, and also identify those who may be eligible for enrolment in alternative therapeutic studies such as PROTECT-V, as they become available.”

What’s next for immunosuppressed patients?

As well as highlighting which patients need to remain cautious, the study will also identify those who may benefit from being enrolled in trials that are testing additional ways to protect patients from Covid-19, such as PROTECT-V. This is a study we are helping to fund which is investigating whether niclosamide, a drug usually used to treat tapeworms, can prevent COVID-19 infection in vulnerable, high risk kidney patients.

Dr Michelle Willicombe, study lead said: “The MELODY study aims to assess the antibody status of immunocompromised people in the community who have received at least three vaccines.

“It focuses on a population who are in need of bespoke COVID-19 protection strategies. As well as antibody testing, the study will capture information on clinical and social factors, which will enable the identification of those immunocompromised patients who are most at risk.”

Find out more

Transplant recipients may self-register by going to

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

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