Thousands of volunteers will get a booster coronavirus vaccine as part of a world-first clinical trial in the UK, the health secretary has announced.
The Cov-Boost study will trial seven COVID-19 vaccines and will be the first to provide data on the impact of a third vaccine dose.
It will give scientists and experts a better idea of the impact of a booster dose in protecting people from COVID.
The study will be led by University Hospital Southampton NHS Foundation Trust and supported with £19.3m of government funding.
Some 2,886 people aged 30 and older will be recruited at 18 NHS sites from London to Glasgow and the first booster jabs will be administered in early June.
Initial findings are expected in September.
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.
"I urge everyone who has had both doses of a COVID-19 vaccine, and is eligible, to sign up for this study and play a part in protecting the most vulnerable people in this country and around the world for months and years to come."
People who received their first dose of either the AstraZeneca or Pfizer/BioNTech vaccine in December or January are being encouraged to take part, as well as those aged 75 and over.