How safe is the AstraZeneca vaccine?

UK regulator says under-30s should be given an alternative jab over blood clot concerns

Boris Johnson AstraZeneca
Boris Johnson at the AstraZeneca factory in Macclesfield
(Image credit: Dave Thompson/WPA Pool/Getty Images)

The UK medicines regulator has said people under 30 should be offered an alternative to the Oxford-AstraZeneca vaccine due to concerns about rare and unusual blood clotting.

As a precautionary measure, people aged 18 to 29 should be given the Pfizer or Moderna vaccine instead, said the Medicines and Healthcare products Regulatory Agency (MHRA).

The regulator said there was not yet proof that the jab had caused the clots, but that evidence of such a link was “firming up”. It stressed that the cases were extremely rare and, for most age groups, the benefits of getting vaccinated outweigh the risks.

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What are the blood clot concerns?

Regulators in the UK and Europe have been investigating reports of rare blood clotting cases combined with low platelet counts in people who have been vaccinated with the Oxford-AstraZeneca jab.

Data released by the MHRA today during a news conference identified 79 cases, 19 of them fatal, of rare blood clots, out of more than 20 million doses given. Overall, there were 51 women and 28 men among the cases, with ages ranging from 18 to 79. They included cases of a specific type of clot known as cerebral venous sinus thrombosis (CVST), which stops blood from draining from the brain.

The agency suggested the risk factor for such clots is around four in a million.

What else has the MHRA said?

Dr June Raine, chief executive of the MHRA, said the benefits for older people of having the AstraZeneca vaccine far outweigh the blood clot risks, but she said it is more “finely balanced” in young people who are less likely to die from Covid.

Anyone with the following symptoms after their vaccine should seek medical help:

  • Headaches
  • Blurred vision
  • Shortness of breath
  • Chest pain
  • Leg swelling
  • Abdominal pain
  • Bruising or pinpoint spots beyond the vaccination site

What are other countries doing?

The jab has had a “mixed international reception”, reported The Times last week. Britain has been - so far - “staunchly supporting its use”, while South Africa “outright rejected” it, the newspaper continues.

On Friday, the Netherlands became the latest country to stop the vaccine for under-60s. Several EU countries suspended the vaccine last month before restarting their rollouts after the European Medicines Agency (EMA) said the benefits outweighed the risks. But a “patchwork of age restrictions” remains in place, and Canada halted the use of the jab for under-55s last week “pending further analysis”.

The EMA, which held a separate news conference at the same time as the MHRA today, said unusual blood clots with low blood platelets should now be listed as a very rare side effect, confirming a “possible link” between the two. However, it backed the vaccines’ use in all adults.

“Covid-19 is associated with a risk of hospitalisation and death,” the EMA said. “The reported combination of blood clots and low blood platelets is very rare, and the overall benefits of the vaccine in preventing Covid-19 outweigh the risks of side effects.”

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