Rare cases of blood clots and low platelets after vaccination
16 April 2021
Publish date: 04 February 2021
The world’s first COVID-19 vaccine study researching alternating doses and intervals of approved vaccines is taking place at UCLH.
The study will determine the effects of using a different vaccine for the second dose to the first dose, in addition to two different intervals between doses.
The study, classified as an Urgent Public Health study by the National Institute for Health Research (NIHR), is being undertaken 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 NIHR-supported sites in England.
The study will gather immunological evidence on different intervals between the first and second dose for a mixed-vaccine regimen against control groups when the same vaccine is used for both doses.
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).
Professor Vincenzo Libri, Director of the NIHR UCLH Clinical Research Facility and the UCLH Vaccine Research Centre, who is Principal Investigator of the trial at UCLH, said:
“We are excited to begin this important study at our vaccine research centre at UCLH. We have made great progress over recent months in vaccine research and roll out – and this study will provide vital information about vaccine combinations and intervals. We would like to encourage people from all sections of the community to take part in this study.”
The study will initially have eight different arms, testing eight different combinations, but more products may be added:
The 13-month study will monitor the impact of the different dosing regimens on patients’ immune responses, which have the potential to be higher or lower than from the same dose regimen.
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 and further COVID-19 vaccine studies by joining the registry or visiting www.comcovstudy.org.uk 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.
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 UK public can continue to support the national effort to speed up vaccine research and receive more information about volunteering for future vaccine studies by visiting www.nhs.uk/researchcontact.
Image: Alernon77 / Adobe Stock
14 April 2021
14 April 2021