The EU medicines regulator has ruled the "benefit of the AstraZeneca jab outweighs the risks", but has decided that blood clots should be added as a very rare side effect of the vaccine.
The European Medicines Agency (EMA) reiterated that the AstraZeneca vaccine had been “proven to be highly effective” and that vaccination as a whole is “extremely important” in the fight against Covid-19.Emer Cooke, executive director of the EMA, said its review “confirmed that the benefits of the AstraZeneca vaccine in preventing Covid-19 overall outweigh the risk of side effects", but concluded that "unusual blood clots with low blood platelets should be listed as very rare side effects".
Meanwhile the UK regulator concluded that under 30s in the UK will be offered the Moderna or Pfizer vaccine instead of the AstraZeneca jab where possible, due to the very rare risk of blood clots.
Blood clot concerns are not new and in fact, have been brewing in the last few weeks. Here is a look back at when and how doubts were raised about the AstraZeneca coronavirus vaccine:
March 11 - Denmark and several European countries suspend use of jab
Denmark was the one of the first countries to suspend the rollout of the AstraZeneca/Oxford jab after reports that a 60-year-old woman who was given the vaccine formed a blood clot and died.
There were also other reports of "severe cases of blood clots in people". A person was admitted to hospital in Austria with pulmonary embolism (blockage in arteries in the lungs) after being vaccinated.
But Søren Brostrøm, director of Denmark's National Board of Health, stressed that a link between the vaccine and blood clots had not been concluded, suggesting the suspension was a precaution while authorities investigated.
Norway and Iceland also announced it would suspend the use of the jab. Several other countries - Austria, Italy, Estonia, Lithuania, Luxembourg and Latvia - said they would stop using a batch of the vaccine while investigations continued.
March 12 - 14 - More countries suspend use of jab
Thailand followed the lead of Denmark and several European countries in suspending the use of the AstraZeneca vaccine on March 12. A media event with Thai prime minister Prayuth Chan-ocha receiving his first jab was cancelled less than an hour before the scheduled start.
Ireland followed suit on March 14.
Around the same time, it was revealed that Norway recorded four serious blood clots in adults who have had the jab, leaving them in hospital.
The EMA reported another person in Austria was diagnosed with blood clots and died 10 days after vaccination, but it stressed there was “no indication that vaccination has caused these conditions”.
A 50-year-old man was also thought to have previously died in Italy from deep vein thrombosis (DVT), while there was an unconfirmed report of another death in Italy.
Meanwhile, the UK’s Medicines and Healthcare products Regulatory Agency (MHRA) said evidence had not confirmed the vaccine caused the problems, and said people should still get their vaccine.
AstraZeneca said analysis of more than 17 million vaccine doses administered did not show evidence of an increased risk of blood clots. It said the reported numbers of blood clots were "not greater than the number that would have occurred naturally in the unvaccinated population".
AstraZeneca said it was reviewing its safety data and the EMA also initiated an urgent review of all blood clotting events occurring with the vaccine.
Professor Andrew Pollard, head of the team who developed the Oxford/AstraZeneca jab, reassured people on BBC Radio 4’s Today programme. He said more than 11 million doses had now been given in the UK and MHRA had said “very clearly that they’re not seeing any increase in the number of cases of blood clots” over what they would see normally.
Professor Anthony Harnden, deputy chairman of the Joint Committee on Vaccination and Immunisation, also said there was “no demonstrable difference” in the number of blood clots seen between the general population and the 11 million who had received the jab.
He said: "I spent all yesterday in our practice vaccinating with the Oxford/AstraZeneca vaccine – I would not be immunising my own patients unless I felt it was safe."
He added: "One ought to also remember that Covid causes blood clots. So, the risks of not having the Covid vaccination far outweigh the risks from the vaccinations."
March 18 - EMA and MHRA says jab is safe
The EMA said the jab was “safe and effective”. It said there was no proven link between the jab and blood clots but could not rule out that link either.
Emer Cooke, the EMA executive director, said the benefits “outweigh the possible risks” and recommended the possible risks are included in the product information.
The UK’s MHRA likewise said there was "no proven causal association" between five reports in the UK of a "unique" blood clot and the AstraZeneca jab.
It said it would continue to investigate any link between a "very rare and specific type of blood clot in the cerebral veins".
The clot – cerebral venous sinus thrombosis (CVST) – prevents blood from draining out of the brain.
March 19 - European countries resume use of jab
Germany, France, Italy, Spain, Portugal and the Netherlands said they would resume use of the AstraZeneca jab after it was ruled to be safe by both the UK and EU's regulators.
March 30 - Fresh concerns as Germany restricts use of jab
German health officials agreed to restrict the use of the AstraZeneca vaccine in people under 60, amid fresh concern over unusual blood clots reported in a tiny number of those who received the shots.
The country’s medical regulator released new data showing a rise in reported cases of an unusual form of blood clot in the head — known as sinus vein thrombosis — in recent recipients of the AstraZeneca vaccine.
But out of 2.7 million people who received the jab in Germany, only 31 blood clots have been reported.
Nine of the people died and all but two of the cases involved women, who were aged 20 to 63, the Paul Ehrlich Institute said.
April 3 - Small causal link between AstraZeneca jab and blood clots, expert suspects
The evidence is shifting towards a very small but causal link between rare blood clots and the Oxford/AstraZeneca Covid-19 vaccine, Professor Paul Hunter, a medical microbiologist at the University of East Anglia, told the BBC Radio 4 Today programme.
The Medicines and Healthcare products Regulatory Agency (MHRA) said on April 2 it had identified 30 cases of rare blood clot events out of 18.1 million doses of the jab administered up to March 24.
There have been seven deaths among the 30 cases, including 22 reports of cerebral venous sinus thrombosis (CVST) and eight of other thrombosis events with low platelets.
But Professor Hunter said the risks of taking the AstraZeneca vaccine are still far outweighed by the risks of not getting the jab.
April 6 - Vaccine trials for children halted
The trial of the AstraZeneca jab in children has been paused while regulators investigate a potential association between the jab and a rare form of blood clot.
The University of Oxford said no safety concerns have arisen from the trial itself. But it is waiting for more information from the MHRA before giving any more vaccination.
On the same day, Channel 4 News reported two senior sources had revealed the MHRA was being urged to restrict the AstraZeneca jab in younger people, at least those under 30 years old.
It comes amid concerns the risk of extremely rare blood clots could be marginally higher among younger people.
Meanwhile, vaccines minister Nadhim Zahawi urged people who are offered a Covid-19 vaccine to take up the offer.
April 7 - Under-30s in UK will be offered Pfizer or Moderna vaccines instead
The UK's Medicines and Healthcare products Regulatory Agency confirmed in a briefing that under-30s in the UK will be offered Pfizer or Moderna vaccines rather than the Oxford/AstraZeneca vaccine due to concerns over a very rare risk of blood clots.
MHRA chief executive Dr June Raine said the benefits of the AstraZeneca vaccine outweigh the risks for the “vast majority” of people after cases of blood clots were detected in an “extremely small” number of people.
The EMA at the same time ruled the benefits of the AstraZeneca jab outweigh the risks, but that blood clots should be added as a very rare side effect of the vaccine.
Although it found that most of the cases of blood clots reported occured in women under 60, it said it could not conclude on whether age or gender played a factor on the risk.
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