A new clinical trial will investigate whether a third dose of vaccine for people with weakened immune systems gives a stronger immune response than two doses.
The study, OCTAVE DUO, will offer people who are immunosuppressed or immunocompromised a Pfizer, Moderna or Novavax vaccine to determine whether this will give a stronger immune response than 2 doses. 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.
The OCTAVE trial has published preliminary data showing that 89% of people who are immunocompromised or immunosuppressed generate antibodies following vaccination, and 60% 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. 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 the virus. These findings therefore do not provide a conclusive assessment of the protection vaccines offer people with weakened immune systems.
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 University of Glasgow and University of 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.
A separate study by Public Health England (PHE) in July which looked at antibody response and vaccine effectiveness against symptomatic infection 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.
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.
Patients included in the OCTAVE DUO study are people with:
- 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
- hepatic and intestinal disease
- primary immune deficiency
Professor Iain McInnes, Head of the College of Medical, Veterinary and Life Sciences at the University of Glasgow who leads the OCTAVE and OCTAVE DUO studies, said: "It is hugely important for us to urgently understand the effectiveness of COVID-19 vaccines in people who have immune-mediated inflammatory diseases, cancer, and diseases of the kidney or liver.
"Our first study to answer this question is the OCTAVE study which has shown that there is a group of patients who may not mount a sufficient immune response. We are pleased to now roll-out the OCTAVE DUO trial, to investigate the effects of a third dose on this particular group of patients who have shown an undetectable or low vaccine response. We hope to provide answers to this very important unanswered question."