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Lower COVID-19 vaccine booster dose study launches in Southampton

Volunteers from Southampton and the surrounding area are set to receive a third lower COVID-19 vaccine booster dose through the COV-BOOST study.

The COV-BOOST: Young Adults Fractional Dosing Sub-study is being led by University Hospital Southampton NHS Foundation Trust.

Why give lower doses to young people?

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.

Volunteers needed

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 between 18 to 30 years old who have had two doses of the Pfizer or Moderna COVID-19 vaccines but have not received a booster.

People who have tested positive for COVID-19 in the past can also take part in the study.

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 to find out more and sign up.”

Taking part

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 are also being recruited through the NHS COVID-19 Vaccine Research Registry, 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.


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