Alternating vaccines trial expands to include two additional vaccines

Wednesday, 14 April 2021

Experts from the University of Nottingham are looking for people who have had their first Covid-19 vaccination in the past 8-12 weeks, to take part in an extended study investigating alternating doses of two new approved vaccines.

Researchers who were part of the Com-Cov study, launched in February to investigate alternating doses of the Oxford-AztraZeneca vaccine and the Pfizer vaccine, have today announced an extension to this programme, to include the Moderna and Novavax vaccines in a new study.

The trial is led by the University of Oxford, run by the National Immunisation Schedule Evaluation Consortium (NISEC), and backed through funding from the Vaccines Task Force and the Coalition for Epidemic Preparedness Innovations.

As one of the trial sites, experts from the University of Nottingham are looking to recruit 100 participants, aged 50 years and over, who have already received their first Covid-19 vaccination, to receive their second vaccine at the Cripps Health Centre on University Park in Nottingham on either the 26 or 27 April.

To be eligible locally, people must have received their first Covid-19 vaccine between the 1 February and the 1 March (if they attend on the 26 April), or the 2 February and the 2 March (if they attend on the 27 April).

These volunteers, who will have received either the Oxford-AstraZeneca, or Pfizer vaccine, will be randomly allocated to receive either the same vaccine for their second dose, or a dose of the Covid-19 vaccines produced by Moderna or Novavax.

Working across a total of eight sites in the UK, researchers will study reactogenicity (any adverse reactions) and the immune system responses to these new combinations of vaccines. The study is designed as a so-called ‘non-inferiority’ study and will compare the immune system responses to the gold-standard responses reported in previous clinical trials of each vaccine.

If the study shows promising results, the regulators MHRA and JCVI would formally assess the safety and efficacy of any new vaccination regimen before it would be rolled out to patients.

This is an important next step in studying the effects of alternating different vaccines in patients. With new vaccines continuing to be approved all the time, if we show the immune response to mixed vaccine schedules is as effective as with the two doses of the same vaccine, then this could lead to more people being able to have their complete vaccination course more quickly. It will also reduce the risk of supply issues with each vaccination.”
Professor David Turner from the University of Nottingham, and Honorary Consultant in Clinical Microbiology at Nottingham University Hospitals NHS Trust, and Principal Investigator on the study

Matthew Snape, Associate Professor in Paediatrics and Vaccinology at the University of Oxford, and Chief Investigator on the trial said: “The focus of both this and the original COM-COV study is to explore whether the multiple Covid-19 vaccines that are available can be used more flexibly, with different vaccines being used for the first and second dose.

“If we can show that these mixed schedules generate an immune response that is as good as the standard schedules, and without a significant increase in the vaccine reactions, this will potentially allow more people to complete their Covid-19 immunisation course more rapidly. We saw a fantastic response to the public from the original COM-COV study, with 830 participants recruited over eight sites in a two-week period in February. We look forward to working with this network and several new sites for the COM-COV2 study.”


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The University of Nottingham is a research-intensive university with a proud heritage. Studying at the University of Nottingham is a life-changing experience and we pride ourselves on unlocking the potential of our students. We have a pioneering spirit, expressed in the vision of our founder Sir Jesse Boot, which has seen us lead the way in establishing campuses in China and Malaysia - part of a globally connected network of education, research and industrial engagement. Ranked 103rd out of more than 1,000 institutions globally and 18th in the UK by the QS World University Rankings 2022, the University’s state-of-the-art facilities and inclusive and disability sport provision is reflected in its crowning as The Times and Sunday Times Good University Guide 2021 Sports University of the Year. We are ranked eighth for research power in the UK according to REF 2014. We have six beacons of research excellence helping to transform lives and change the world; we are also a major employer and industry partner - locally and globally. Alongside Nottingham Trent University, we lead the Universities for Nottingham initiative, a pioneering collaboration which brings together the combined strength and civic missions of Nottingham’s two world-class universities and is working with local communities and partners to aid recovery and renewal following the COVID-19 pandemic.

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