St George’s joins world’s first Covid-19 vaccine alternating dose study
Published: 04 February 2021
Image by Gabby K on Pexels
A new vaccine study, launching today, will be the first in the world to test alternating doses of different Covid-19 vaccines, as well as different intervals between doses. The Vaccine Institute at St George’s will be one of eight sites in England participating in the trial as part of the National Institute for Health Research (NIHR) Clinical Research Network (CRN) North Thames and South London regions.
The NIHR-supported study will determine the effects of using different already-approved vaccines for the second dose to the first dose, in addition to two different intervals between doses of 28 days apart compared to 12 weeks apart. The study will gather immunological evidence and compare against control groups who will receive the same vaccine for both doses.
The study, classified as an Urgent Public Health study by the NIHR, is being led by the National Immunisation Schedule Evaluation Consortium (NISEC) and the Oxford Vaccine Group, and is backed by £7 million of government funding from the Vaccines Taskforce.
Over 800 volunteers, aged 50-years-old and above, are expected to take part in the study referred to as the COVID-19 Heterologous Prime Boost study, or ‘Com-Cov’, across eight sites, including in London, Birmingham and Liverpool.
While this study is testing alternating doses of different vaccines, a same-dose regimen is currently implemented for the national Covid-19 vaccination programme, and there are no current plans for this to change. Anyone who has received either the Pfizer or AstraZeneca vaccination as part of the UK-wide delivery plan will not be affected by this study. They will receive their second dose from the same source and over the same 12-week interval.
The clinical study will monitor the impact of the different dosing regimens on patients’ immune responses, and whether this can be a viable route to increase the flexibility of the UK’s vaccination programme. It has received ethics approval, as well as approval from the Medicines and Healthcare products Regulatory Agency (MHRA) to commence.
Should the study show promising results, then the government may consider reviewing the vaccine regimen approach if needed, but only if proven to be safe and recommended by the Joint Committee on Vaccination and Immunisation (JCVI).
The study will initially have eight different arms, testing eight different combinations, but more products may be added:
- Oxford/AstraZeneca and Oxford/AstraZeneca - 28 days apart
- Oxford/AstraZeneca and Oxford/AstraZeneca - 12 weeks apart - as a control group
- Pfizer/BioNTech and Pfizer/BioNTech - 28 days apart
- Pfizer/BioNTech and Pfizer/BioNTech - 12 weeks apart - as a control group
- Oxford/AstraZeneca and Pfizer/BioNTech - 28 days apart
- Oxford/AstraZeneca and Pfizer/BioNTech - 12 weeks apart
- Pfizer/BioNTech and Oxford/AstraZeneca - 28 days apart
- Pfizer/BioNTech and Oxford/AstraZeneca - 12 weeks apart
Patients are to be recruited over the course of February via the NHS COVID-19 Vaccine Research Registry, with vaccinations expected to start towards the middle of the month and initial results to be made available over the summer period. The UK public can volunteer to be contacted about taking part in the study by visiting the Com-Cov study website to find out more and see if there is a study site near them.
If the study shows promising results, the MHRA would formally assess the safety and efficacy of any new vaccination regimen before it would be rolled out to patients.
Professor Paul Heath, Director of the St George’s Vaccine Institute and Principal Investigator for the study at St George’s, said: “The results of this research could allow us to save even more lives by enabling people to be vaccinated more quickly and efficiently against this terrible disease. We encourage as many people as possible to sign up for this study.”
Deputy Chief Medical Officer and Senior Responsible Officer for the study, Professor Jonathan Van-Tam said: “Given the inevitable challenges of immunising large numbers of the population against Covid-19 and potential global supply constraints, there are definitely advantages to having data that could support a more flexible immunisation programme, if ever needed and approved by the medicines regulator.
“It is also even possible that by combining vaccines, the immune response could be enhanced giving even higher antibody levels that last longer; unless this is evaluated in a clinical trial we just won’t know.
“This study will be a promising opportunity to gain greater insight into how we can use the vaccines to stay on top of this nasty disease.”
The Covid-19 vaccine trials extend a portfolio of research at St George’s to tackle the coronavirus pandemic. The University has launched a Coronavirus Action Fund to raise money for vital research into the pandemic and is actively seeking support for a broad research programme involving all parts of the University.