The U.K.’s drug regulator will address safety concerns surrounding AstraZeneca Plc’s COVID-19 vaccine on Wednesday, as fears grow that the government’s inoculation targets will be put at risk.

Representatives from the U.K.’s Medicines and Healthcare products Regulatory Agency and the government’s vaccine committee will speak at 3 p.m., at the same time as the European Medicines Agency holds its own press briefing.

They will update on their investigations into potential links between the AstraZeneca vaccine, which was developed with Oxford University, and rare cases of brain blood clots in adults. On Tuesday, a trial of the Astra vaccine among children was paused to await the findings of the U.K. review.

It comes as a vaccine by Moderna Inc. began to be rolled out in the U.K. for the first time, the third approved coronavirus shot alongside those from Astra and partners Pfizer Inc. and BioNTech SE. The U.K. has ordered 17 million doses of Moderna’s two-shot vaccine, enough for 8.5 million people.

The success of the vaccine program is crucial to Prime Minister Boris Johnson’s ambition to fully reopen the U.K. economy on June 21. The U.K. has ordered 100 million doses of the Astra vaccine, and 40 million doses of Pfizer.


Concerns are growing that a setback with the Astra shot could mean the U.K. misses its target to vaccinate all adults by the end of July, although the government insists it remains on track.

The pound extended losses ahead of the briefing, hitting its weakest level against the euro in a month.

Visitors enter a COVID-19 vaccination centre at Guys hospital in London, The City of London, U.K., on Monday, Feb. 15, 2021. The U.K. recorded 15 million vaccinations against the coronavirus, a milestone that is set to increase pressure on Prime Minister Boris Johnson to begin reopening the economy.

U.K. ministers have repeatedly said the benefits of the vaccine in preventing coronavirus far outweigh any risks.

‘No Proof’

“There is no proof as yet that there is any causal links on the very, very rare occasions that there have been talks about blood clots,” Business Minister Paul Scully told Sky News on Wednesday. “The AstraZeneca vaccine is safe; it has saved thousands of lives.”

But some scientists have urged caution while investigations are carried out. Maggie Wearmouth, a member of the U.K.’s Joint Committee on Vaccination and Immunization, suggested that “perhaps slowing things down” 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.”

Adam Finn from the University of Bristol, also a member of the JCVI, said it was possible that Moderna or other vaccines could be reserved for younger groups in case Astra’s use was restricted.

‘On Track’

Vaccination centers and pharmacies are facing a “significant reduction” in supply of doses during April, meaning that older people waiting for second doses will be prioritized over younger people getting their first shot.

The pace of the rollout across England is now estimated at an average of 2.7 million doses a week until the end of July -- “considerably slower” than a previous forecast of 3.2 million a week, according to a modeling paper from scientists on a government advisory committee.

A vial on top of a box of COVID-19 vaccine, manufactured by Moderna Inc., in cold storage at the COVID-19 vaccination center inside France's national velodrome in the Saint-Quentin-en-Yvelines district of Paris, France, on Wednesday, March 24, 2021. The French government aims to have immunized 10 million people by mid-April, 20 million in mid-May and 30 million mid-June -- slightly less than half of the total population.

“There will be a slight reduction in April, but the key thing to remember is that that doesn’t mean that we’re not on track to meet our pledges,” said Johnson’s official spokesman Jamie Davies.

The U.K. remains “on track” to offer a first dose to all over-50s by April 15, and to all adults by the end of July, he added.

Three in five adults in the U.K. have been vaccinated so far and the most recent government data shows that more than 31.6 million people have received a first dose, and 5.5 million have had a second dose.

On a visit on Tuesday to an Astra manufacturing plant in Macclesfield, northwest England, Johnson urged people to keep getting their shots: “keep going out there, get your jab, get your second jab.”