New trials of coronavirus vaccinations will start in Wales "within weeks".
A top scientist who works for the body responsible for organising the pilots said different vaccines will be trialed across parts of Wales "very soon".
About 500 volunteers in the Gwent area have already taken part in trials of the Covid-19 vaccine being developed by AstraZeneca and Oxford University.
The new trials will be for different vaccines, but Health and Care Research Wales would not confirm which products.
"We're working with vaccines developed by others and they are searching for locations to trial their vaccinations," said Dr Angharad Davies, Health and Care Research Wales' lead for infection.
"Although we're not developing the vaccines ourselves, it is a lot of work.
"We're looking at starting the trials very soon - within the next month or two. They will be held across Wales.
"Some will be in the Aneurin Bevan Health Board area in Gwent, some will be in Cardiff and there will be others in north Wales - they will probably be with a different vaccination."
Wales' 17-day national lockdown started on Friday as the Welsh Government aims to slow the surge in Covid-19 cases and hospital admissions by ordering people to stay at home and closing non-essential shops, pubs, restaurants and hotels.
More than 40,000 people have tested positive and 1,756 people have died with Covid-19 in Wales since the first case at the end of February. There have been more than 41.5 million cases across the world and more than one million deaths.
Vaccines are designed to train the immune system in a highly targeted way that leaves lasting protection against one particular infection.
Immunisation is often seen as the holy grail that will end the Covid-19 pandemic, but a report from researchers brought together by the Royal Society said people needed to be "realistic" about what a vaccine could achieve and when.
Some 200 different vaccines are being developed across the world, with some countries already using vaccinations developed by their own scientists. Some scientists fear, however, these vaccines may not have been tested rigorously enough.
Dr Davies understand 10 vaccinations have now reached a stage in the development process where researchers feel it "seems safe to administer and creates a response from the immune system".
"It then needs to be tested to see whether it can prevent infection - and whether it is safe on a large scale, looking at potential rarer side-effects," she added.
Health boards across Wales are preparing a mass immunisation programme for when - or if - a vaccine becomes available.
But one of Wales' top drug professors has warned "history is against us" when finding a cure against "this family of viruses".
"It could be a very long time until a vaccine is found which is both safe and effective, and there is no certainty one will appear," said Arwyn Tomos Jones, Professor of Membrane Traffic and Drug Delivery at Cardiff University.
"If everything worked perfectly, there would be hope of a vaccine in around a year I'd say.
The Welsh Government have confirmed they are working with Public Health Wales and the UK government on plans to distribute the vaccine when one becomes available.
Those facing the highest risk will likely be immunised first, with priority being decided at a UK level by an expert committee.