A third coronavirus vaccine is being rolled out in the UK, as investigations continue into a potential association between the Oxford/AstraZeneca jab and a rare form of blood clot.
People in Wales will receive the first doses of the Moderna vaccine on Wednesday.
The UK has bought 17 million doses of that vaccine – enough for 8.5 million people.
Jabs will be given out at West Wales General Hospital in Carmarthen in what has been hailed as “another key milestone” in the fight against coronavirus.
It comes as a trial of the Oxford/AstraZeneca vaccine in children has been paused while regulators investigate reports of a rare form of blood clot among adults.
The University of Oxford said no safety concerns have arisen from the children’s trial and Sage adviser Professor Calum Semple said the decision to pause had been made out of “exceptional caution”, as he urged people to continue accepting Oxford/AstraZeneca jabs.
Assessments are under way into a very rare and specific type of blood clot in the brain, known as cerebral venous sinus thrombosis (CVST), occurring together with low levels of platelets (thrombocytopenia) following vaccination in adults.
The World Health Organisation (WHO) and the European Medicines Agency (EMA) are expected to announce findings of their assessments on Wednesday or Thursday.
The UK’s regulator – the Medicines and Healthcare products Regulatory Agency (MHRA) – is also investigating reports but has not confirmed when it will present its findings.
Both the MHRA – which said it had identified 30 cases of rare blood clot events out of 18.1 million doses of the jab administered up to and including March 24 – and WHO have said that to date the benefits of the vaccine in preventing coronavirus outweigh any risks.
Dr Maggie Wearmouth, a member of the Joint Committee on Vaccination and Immunisation (JCVI), indicated that “perhaps slowing things down” with the rollout “until we’re absolutely certain” might be wise.
Speaking in a personal capacity, she told the Daily Telegraph: “The issue is about safety and public confidence. We don’t want to cover anything up that we feel that the public should be knowing.
“We’re not here to blindly follow targets or due dates. We will do what is necessary.”
Fellow JCVI member Professor Adam Finn said the situation must be “addressed urgently”.
Speaking in a personal capacity, he told BBC Newsnight: “It’s clear that everyone is taking these cases enormously seriously, we do need to get to the bottom of this.
“We are walking a tightrope here between the need for speed but also the need for clarity and scientific certainty about what’s going on and of course the public wants to know, so very important issues that need to be addressed urgently.”
Health Secretary Matt Hancock said he was “delighted we can start the UK rollout of the Moderna vaccine in west Wales today”.
He added: “The UK government has secured vaccines on behalf of the entire nation and the vaccination programme has shown our country working together at its best.”
Wales Health Minister Vaughan Gething said: “This is another key milestone in our fight against the Covid-19 pandemic.”
The rollout will start in England “as soon as possible this month”, a spokesperson for the Department of Health and Social Care said, but added that commercial sensitivities prevented further disclosures.
Vaccines minister Nadhim Zahawi said on Tuesday that the Moderna jab would be deployed “around the third week of April”.
Scotland’s First Minister Nicola Sturgeon said the first batch of Moderna vaccines had arrived in the country on Monday and will be delivered over the coming months.
It has not been confirmed when the rollout of Moderna will begin in Northern Ireland.
More than 31 million first doses of either the Pfizer or AstraZeneca vaccines have been administered in the UK, according to Government data up to April 5, while more than five million second doses have been given out.
The potential role of “Covid status certification” – which has drawn criticism from some Tories as well as Labour – in certain settings to reduce social distancing restrictions hit a snag when a comedy club pulled out of a pilot after accusing the Government of failing to clarify whether it would involve vaccine passports.
The Hot Water Comedy Club in Liverpool said it had been the target of a “hate campaign” online after reports suggested it was working with the Department for Digital, Culture, Media and Sport (DCMS) to trial such certification.
A Government spokesperson said they “strongly condemn” the online abuse the club received and confirmed the initial pilot events would be based on proof of a negative test result rather than any requirement for people to have had a jab.
Meanwhile, a study has suggested contracting Covid-19 is “robustly associated” with an increased risk of developing mental health and neurological conditions in the six months after a diagnosis.
Researchers at the University of Oxford estimated that one in three virus survivors (34%) were diagnosed with a neurological or psychiatric condition within six months of being infected.