The Welsh Government has said it does not see any delay to the vaccination rollout, after the UK medicines regulator held a briefing advising that people under thirty are given an alternative to the Oxford/AstraZeneca jab following blood clot concerns.
On Wednesday afternoon the Medicines and Healthcare products Regulatory Agency (MHRA) announced that, despite the vaccine offering high levels of protection from coronavirus, there was a growing link between the Oxford/AstraZeneca jab and rare blood clots.
In a statement, the Welsh Government said the vaccine remained safe and insisted the change in medical advice would not delay Wales' vaccination rollout in any way.
A spokesperson said: "We are considering the details of today’s announcements by the MHRA and the JCVI but we do not envisage a delay to the roll out of our vaccine programme in Wales.
"The Oxford AstraZeneca (OAZ) vaccine remains safe and effective and has already saved thousands of lives.
"The Welsh Government, Public Health Wales and NHS Wales are working with other agencies to continually monitor vaccine safety and will keep this issue under close review.
"In Wales, people’s safety will always come first and we will only use vaccines where it is safe to do so and the benefits continue to outweigh the risks."
The Government added that anyone who has already had a first dose of the Oxford/AstraZeneca vaccine will be able to receive a second dose regardless of their age.
"Everybody who has already had a first dose of the OAZ vaccine should be reassured that they can receive a second dose of the same brand, irrespective of age," the statement said.
Professor Wei Shen, chairman of the JCVI, said the recommendation to prefer other vaccines to AstraZeneca for the under-30s was "out of the utmost caution" rather than because of "any serious safety concerns".
The MHRA said that those who have had their first dose of the AstraZeneca vaccine should still get their second dose.
Only those who suffered a rare blood clot after the first dose should not get vaccinated.
Anyone with blood disorders that leave them at risk of clotting should discuss the benefits and risks of vaccination with their doctor before going for a jab.
Up to March 31, the MHRA has received 79 reports of blood clots accompanied by low blood platelet count, all in people who had their first dose of the vaccine, out of millions of doses given.
Of these 79, a total of 19 people have died, although it has not been established what the cause was in every case.
The 79 cases occurred in 51 women and 28 men, aged from 18 to 79.
Of the 19 who died, three were under the age of 30, the MHRA said.
Some 14 cases of the 19 were cerebral venous sinus thrombosis (CVST), a specific type of clot that prevents blood from draining from the brain.
The other five cases were other kinds of thrombosis in major veins.
A trial of the UK's main coronavirus vaccine on around 300 children was paused on Tuesday while the Medicines and Healthcare products Regulatory Agency (MHRA) investigates the possibility of links to a rare blood clotting syndrome in adults.
The University of Oxford said that no safety concerns had arisen from the trial itself but decided to pause the trial ahead of a ruling from the MHRA.
An Oxford University spokesperson said on Tuesday: "Whilst there are no safety concerns in the paediatric clinical trial, we await additional information from the MHRA on its review of rare cases of thrombosis/thrombocytopaenia that have been reported in adults, before giving any further vaccinations in the trial.
"Parents and children should continue to attend all scheduled visits and can contact the trial sites if they have any questions."