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COVID-19 vaccine lower booster dose study launches in London

Volunteers from London are set to receive a third COVID-19 vaccine lower booster dose through the COV-Boost study.

The COV-Boost: Young Adults Fractional Dosing Sub-study will open at four London sites:

  • University College London Hospitals (UCLH)
  • Guy’s and St Thomas’ NHS Foundation Trust
  • St George's University Hospitals NHS Foundation Trust
  • Northwick Park Hospital (London North West University Healthcare NHS Trust)

Young adults have a stronger immune response to vaccines than older adults, and results from COVID-19 vaccine studies have suggested lower doses of the Pfizer or Moderna COVID-19 vaccines may give as good an immune response in young adults as higher doses. Lower doses may also be linked with fewer side effects or lower rates of already rare adverse events.

Using lower doses could allow existing stocks of vaccines to be given to more people, which is important while the need for vaccines is greater than the number of doses available globally.

Participants will be randomly selected to receive one of the following doses:

  • A single dose of Pfizer (currently used in the UK booster programme)
  • One third of a single Pfizer dose (currently recommended for 5-11 years old in the UK)
  • A half Moderna dose (the dosage used by the NHS as a 3rd dose booster)
  • One quarter of a single Moderna dose

The NIHR-supported study is looking for volunteers who are:

  • between 18 to 30 years old
  • have had two doses of the Pfizer or Moderna COVID-19 vaccines, with at least 3 months (84 days) since their second dose
  • have not received a booster

People who have tested positive for COVID-19 in the past, and have had their second vaccine, can also take part in the study.

Anyone interested in finding out more or taking part in the study can visit the COV-Boost website, where they can complete the study questionnaire to see if they are eligible.

Participants will be reimbursed up to £225 for their time, inconvenience and travel, with boosters given in January and into February.

The study will take place at 15 hospitals across England, Wales and Scotland, and will include a total of over 900 participants. All participants will be monitored throughout the study for any potential side effects and will have bloods taken to measure their immune responses on the day of their first visit and then two weeks, one month, three months and eight months following vaccination.

All the trial sites are working on ways of including people in research from a wide variety of backgrounds and individuals from ethnic minorities are encouraged to apply. The study is being led by University Hospital Southampton NHS Foundation Trust.

Professor Saul Faust, Chief Investigator and Director of NIHR Southampton Clinical Research Facility, said:

"The first phase of the COV-Boost study looked at the safety, immune responses and side-effects of seven COVID-19 vaccines when used as a third booster jab. The findings have helped shape the UK booster programme and given important evidence towards global vaccination efforts.

"In this next phase, we are looking for volunteers aged 18 to 30 to help us investigate the safety and side effect profile of giving lower doses of either the Pfizer or Moderna COVID-19 vaccines.

"If we find that giving a lower dose of these vaccines to young adults gives as good an immune response as a higher dose, this could have positive implications for global vaccine supply and may result in a lower side effect profile in this age group.

"Our vital COVID-19 vaccine research would not be possible without support from the public, who continue to step forward to take part in our studies. We need young adults from all backgrounds to take part in this new study and I would encourage anyone interested to visit the COV-Boost website to find out more and sign up."

Professor Andrew Ustianowski, National Clinical Lead for the UK NIHR COVID Vaccine Research Programme said:

"The COV-Boost study has already provided the UK and other countries with extremely valuable data when it comes to understanding how we can boost populations and protect them against COVID-19. The latest phase of the study could also prove very useful and help identify if lower doses can be as effective whilst having other specific advantages.

"We cannot thank participants enough for their commitment to COVID-19 vaccine studies and encourage those who have not yet received a booster to sign up for this study. The UK research community and public have played a huge role working with the NHS and NIHR supported teams to identify several important COVID-19 treatments and vaccines over the last two years. This latest booster sub-study can build upon our strong vaccine data and likely help us find more efficient ways to use vaccine supplies."

Dr Alastair McGregor, Principal Investigator of the study at Northwick Park Hospital, said:

"I'm delighted we can offer local young people the opportunity to take part in this study. The outcomes could have huge implications on vaccine supply and benefit people globally.

"People across the country have been more engaged with research than ever before over the past two years. This study is great for young adults looking to get involved and make a difference."

Professor Paul Heath, Principal Investigator and Director of the Vaccine Institute at St George’s, University of London and St George’s Hospital, said:

"This, the second phase of the COV-Boost study, will allow us to fine tune the vaccine programme even further by identifying the optimal vaccine and dose for boosting young adults. This will have relevance not only for the UK programme but for programmes worldwide." 

At UCLH the study will be led by Professor Vincenzo Libri, Director of the NIHR UCLH Clinical Research Facility (CRF). The study will be conducted at the UCLH Vaccine Research Centre, part of the NIHR UCLH CRF, and it is supported by the NIHR UCLH Biomedical Research Centre.

Professor Libri said: "This study represents an important step towards a better understanding of the optimal dosing of COVID-19 vaccines, both in terms of safety and efficacy. At UCLH we would like to thank all volunteers and research staff for their invaluable support to the trial."

Dr Anna Goodman, Principal Investigator of the study at Guy’s and St Thomas’ NHS Foundation Trust and consultant in infectious diseases, said:

"We are excited for our local community and students to participate in this study and hope to have excellent local uptake. For those who have yet to have a third dose of vaccine, taking part is a way you can help us understand the best way of dosing for the world whilst receiving your own vaccination."

The COV-Boost study published its full initial results in the Lancet in December 2021, which found several COVID-19 vaccines were safe and boosted immunity and its early findings in September 2021 informed the UK’s booster programmeVisit the COV-Boost website to take part in this study.