It is hoped that the booster doses will draw out protection and may also work against new variants of Covid-19.
Seven existing vaccines are to be tested in the Cov-Boost trial, which will include 2,886 participants over 30 across 16 sites in the UK.
Some 185 people will be recruited in Glasgow where 185 participants will be recruited.
The first booster jabs will be administered in early June. One booster will be provided to each volunteer and could be a different brand to the one they were originally vaccinated with.
The £19.3 million clinical trial will test the Valneva jag, made in Livingston, alongside those from Pfizer, AstraZeneca, Moderna, Novavax, Johnson & Johnson and CureVac.
Three of the vaccines will also be tested at a half dose, with experts expecting an adequate immune response at this level.
The half doses will inform whether side-effects are reduced at a lower dose, and could offer useful information to countries where vaccine supply may be more scarce.
The 18 NHS sites across the UK will be split into three groups, with each group testing a different set of vaccines.
All of the information will be fed to to the Joint Committee on Vaccination and Immunisation (JCVI) at the end of August or early September.
Emma Thomson, Professor in Infectious Diseases at Glasgow University Centre for Virus Research, and study lead in Glasgow, said: “This study marks the next step forward in our efforts to understand how to best protect the population and inform future vaccine booster programmes.
“It is the first in the world to provide data on the impact of a third dose and will study seven different vaccines, providing important recommendations for the future.”
Health and Social Care Secretary Matt Hancock said: “We will do everything we can to future-proof this country from pandemics and other threats to our health security, and the data from this world-first clinical trial will help shape the plans for our booster programme later this year.”