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World’s first COVID-19 vaccine alternating dose study launches in Southampton

Published: 4 February 2021
Vaccine
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Southampton is set to help deliver the world’s first COVID-19 vaccine study looking at using different vaccines for first and second doses, and varying the time between doses.

Researchers will look at the impact on individuals’ immune response when using different intervals between the first and second dose for both a mixed-vaccine regimen and for when the same vaccine is used for both doses, as is currently implemented for the national COVID-19 vaccination programme.

The study will be run in the South at the NIHR Southampton Clinical Research Facility (CRF) and University of Oxford’s Centre for Clinical Vaccinology and Tropical Medicine.

Both sites aim to recruit 100 volunteers each, aged 50-years-old and above, to join a further 600 volunteers at six further sites nationally in the study referred to as the COVID-19 Heterologous Prime Boost study, or ‘Com-Cov’.

Anyone from Southampton or Hampshire and Isle of Wight wanting to take part can register online .

Undertaken by the National Immunisation Schedule Evaluation Consortium (NISEC) and the Oxford Vaccine Group, the study is backed by £7 million of government funding from the Vaccines Taskforce, it has received ethics approval, as well as approval from the Medicines and Healthcare products Regulatory Agency (MHRA) to commence.

The study, run at eight National Institute for Health Research (NIHR) supported sites, 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 Saul Faust, Director of the NIHR Southampton CRF and Professor of Paediatric Immunology and Infectious Diseases at the University of Southampton, who is leading the trial locally, said:

“This trial will provide vital data for all our reassurance about the current NHS vaccine roll out, and for how we use COVID-19 vaccines in the future. The people of our city and region contributed massively to the trials that got these vaccines to the front line – we’re hoping they will come forward again to help us use the vaccines as effectively as possible. We’re really keen to hear from those between 50 and 70 years of age, especially those from a black or Asian background. No one taking part will receive a placebo, or dummy, dose – all receive two doses of the currently approved vaccines used by the NHS.”


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


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.

Vaccinations are expected to start towards the middle of February, with initial results to be made available over the summer period.

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.”

Professor Andrew Ustianowski, NIHR Clinical Lead for COVID-19 Vaccination Programme and Joint National Infection Specialty Lead, said:

“This is another exciting step forward in finding a variety of vaccine options for the UK and globally, for which the NIHR is integral to ensuring the participant recruitment for this study and the gaining of robust data on safety and effectiveness.

"We need people from all backgrounds to take part in this trial, so that we can ensure we have vaccine options suitable for all. Signing up to volunteer for vaccine studies is quick and easy via the NHS Vaccine Research Registry."

Matthew Snape, Associate Professor in Paediatrics and Vaccinology at the University of Oxford, said:

“This is a tremendously exciting study that will provide information vital to the roll out of vaccines in the UK and globally. We call on those aged 50 years and above who have not yet received a COVID-19 vaccine to visit the website* to find out more about the study and see if there is a study site near them.

“If we do show that these vaccines can be used interchangeably in the same schedule this will greatly increase the flexibility of vaccine delivery, and could provide clues as to how to increase the breadth of protection against new virus strains.”

* www.comcovstudy.org.uk

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