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New study tests third COVID-19 vaccine for people with weakened immune systems

25/08/2021
Image credit: University of Oxford

Oxford is one of the key centres taking part in a new national clinical trial to determine whether a third dose of COVID-19 vaccine will improve the immune response for people who have weakened immune systems.

The study, OCTAVE DUO, will offer people who are immunosuppressed or immunocompromised by having chronic disease, a Pfizer, Moderna or Novavax vaccine to determine whether this will give a stronger immune response than two doses.

Patients included in the study are people with liver disease (liver transplant, liver cirrhosis and autoimmune liver disease), lymphoid malignancies, immune mediated inflammatory diseases (including rheumatoid arthritis, psoriatic arthritis, vasculitis and inflammatory bowel disease), renal disease, solid tumours (including breast and lung cancers), haematopoietic stem-cell transplantation, and primary immune deficiency.

The £2.2 million study will build on the OCTAVE trial, led by the University of Glasgow and co-ordinated by the University of Birmingham’s Cancer Research UK Clinical Trials Unit. Researchers from Oxford University Hospitals (OUH) and the University of Oxford’s Nuffield Department of Medicine are leading the research involving patients with liver and gastrointestinal diseases.

The OCTAVE trial has published preliminary data showing that 60% of people who are immunocompromised or immunosuppressed generated a strong antibody response following two doses of a vaccine. However, 40% of people in these groups mounted a low or undetectable immune response after two doses, and the level of antibody response varies between the groups studied.

Professor Ellie Barnes, who is leading the Oxford part of OCTAVE DUO, said: "Our work on the OCTAVE study has revealed that 30% of our participating patients in Oxford – and 40% nationally - mount a relatively low immune response to the COVID vaccination. This is of concern, as it means a significant number of vulnerable people may not be protected.

"We need to do more investigations to determine what level of antibody response provides protection against severe COVID. The level of antibodies required for protection from COVID-19 is still not known, and it is likely that T cells also play an important role in protecting people from severe disease. These findings don’t yet provide a conclusive assessment of the protection vaccines offer people with weakened immune systems but measuring the immune response to a third booster vaccine that we can now offer to participants is the right thing to do next."

Dr Michael Lim, senior clinical fellow, said "We have already begun recruitment to OCTAVE DUO here in Oxford. We will investigate the effects of a third vaccine dose on those patients who have shown an undetectable or low vaccine response during OCTAVE. We hope this will help to inform how best to protect patients with immunocompromised or immunosuppressed conditions from COVID-19 infection in future."

Up to 1,200 patients who are already involved in the OCTAVE study or those with other at-risk conditions involved in parallel studies will be recruited to the OCTAVE DUO trial.

The OCTAVE DUO study, co-funded by the government's Vaccines Taskforce and UK Research and Innovation (UKRI) and led by the Universities of Glasgow and Birmingham, will analyse in detail the immune response of this group to the vaccine and the durability of this protection. It will also use healthcare records to determine whether any participants are later diagnosed with COVID-19.

Initial results are expected later this year to inform the UK's COVID-19 vaccine deployment in these specific at-risk groups. The trial will follow the patients to mid-2022 and offer more detailed information at that stage about the immune responses that develop in these groups.

The government is carefully considering the findings of the OCTAVE trial and will also consider any further appropriate advice – including from the independent Joint Committee on Vaccination and Immunisation (JCVI) - for those who are immunosuppressed as part of regular reviews of the latest data and evidence on vaccine efficacy and effectiveness.

A separate study by Public Health England in July which looked at antibody response and vaccine effectiveness against symptomatic infection also showed that those who were immunocompromised had lower antibody responses.

It also found that protection from COVID (vaccine effectiveness against symptomatic disease) for those who are immunosuppressed of all ages after one dose was 4%, but after two doses it was 74%, providing similar protection to those who are not in an at-risk group. Again, vaccine effectiveness may vary by specific condition and severity of that condition.