Video report by ITV Wales journalist Ian Lang
Volunteers near Wrexham are still needed for a world-first clinical trial looking at how effective a coronavirus vaccine booster jab is in protecting people from the virus.
The COV-Boost study, which is being run at Wrexham Maelor Hospital, is taking place at 18 sites around the UK and will involve 2,886 volunteers.
As part of the study, people who have already received their second jab are being given a third to test the impact on their immune system.
Researchers are trying to find out which of seven different Covid-19 vaccines are most effective as a booster vaccination against the virus.
Vaccines being trialled include Oxford/AstraZeneca, Pfizer/BioNTech, Moderna, Novavax, Valneva, Janssen and Curevac.
Health experts say there are still many things we don't know about coronavirus and our immunity to it, and those taking part in the study will help provide answers, particularly as autumn/winter approaches.
ITV News spoke to two volunteers at Wrexham Maelor hospital about their reasons for taking part in the study.
Jayne Gregory said: "It's a valuable service for everybody. I think it's something we need to do to get society and the country going again.
"The vaccines have already proved themselves to be valuable and I think certainly the booster for the autumn will be the thing that keeps us going through the next year."
Rhian Parkinson said: "I thought clinical trials were a good thing to do. I give blood, so you like to think that you're helping people, don't you?"
Public Health Wales is asking over-30s who have had two doses of a Covid-19 vaccine, and who live within a 50-mile radius of Wrexham, to consider take part in the research.
The study is looking to include people from a wide variety of backgrounds and those from ethnic minorities are encouraged to apply.
During Monday's Welsh Government press conference, the First Minister told journalists a Covid booster jab campaign in the autumn may be necessary.
He said any booster jab would be offered to the most vulnerable in society first.
"We still don't know a lot about coronavirus," he said.
"We don't know how long natural immunity lasts; we're not certain how long the vaccine offers protection, and we're seeing new variants as well.
"For all of those reasons, a booster campaign in the autumn may be necessary."
What does the trial involve and how can I take part?
One booster will be provided to each volunteer and it could be a different brand to the one they were originally vaccinated with.
Vaccines being trialled include Oxford/AstraZeneca, Pfizer/BioNTech, Moderna, Novavax, Valneva, Janssen and Curevac. There is also a meningitis vaccine in the mix, which is the control vaccine.
Adults that are aged 30 and over who received their first dose of Covid-19 vaccination in either December 2020, January or February 2021, and who are 84 days post second vaccination, are able to take part.
You must be willing to tell the trial staff about your medical history, and you may be asked to allow the trial staff to check this with your doctor.
If you are able to become pregnant you must be willing to practice continuous effective contraception during the first three months of the trial and have negative pregnancy tests on the days of vaccination.
You must agree not to donate blood during the trial.
For full details, or to sign up, visit the study website.