World's first COVID-19 vaccine alternating dose study launches in Liverpool

• COVID-19 vaccine alternating dose study launched today in the UK
• Study will examine using different vaccines for the two doses, as well as different intervals between doses
• Innovative study backed by £7 million of government funding to recruit over 800 participants across seven UK sites
• Current programme of two doses of the same vaccine over twelve weeks remains unchanged

The world’s first COVID-19 vaccine study researching alternating doses and intervals of approved vaccines, begins today in Liverpool. The National Institute for Health Research (NIHR)-supported study, which will be run by a partnership between Liverpool School of Tropical Medicine (LSTM), the National Institute for Health Research (NIHR) Clinical Research Network: North West Coast and Liverpool University Hospitals NHS Foundation Trust (LUHFT) 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 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 sites across England - including in London, Birmingham and Liverpool.

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).

LSTM's Dr Andrea Collins, Co-Principal Investigator on the trial in Liverpool and North West Coast NIHR Respiratory Speciality Lead, said: “Given Liverpool’s role in the phase 3 Oxford Vaccine trial, we are excited to be taking part in this further study which will give us the opportunity to see if there is any benefit in using the available vaccines interchangeably. The vaccine roll out so far has been a great success and any flexibility can only be advantageous and indeed this ‘mis-match’ approach may provide improved protection.”

Dr Helen Hill, Co-Principal Investigator on the trial in Liverpool, said “Thousands of people in Liverpool and surrounding areas came forward to volunteer to be part of the Phase 3 Oxford vaccine study, we have no doubt they will offer their amazing support once again.”

 For more details https://www.lstmed.ac.uk/news-events/news/worlds-first-covid-19-vaccine-alternating-dose-study-launches-in-liverpool