Speaking at a press conference on Friday, Professor Wei Shen Lim, chairman of the UK Joint Committee on Vaccination and Immunization (JCVI), said the authority had updated its advice for adults to under 40 years old.
Rare blood clots
A very small number of people who have received the AstraZeneca vaccine have suffered from blood clots.
The condition, described by health authorities as “extremely rare,” is characterized by blood clots accompanied by low platelet levels.
As of April 28, the UK Medicines and Health Products Regulatory Agency (MHRA) had received 242 reports of major blood clots associated with a low platelet count occurring after a dose of the AstraZeneca vaccine.
There have been 10.5 cases of blood clots with a low platelet count per million first doses of the AstraZeneca vaccine, the drugs regulator said in its latest report on the side effects of the Covid-19 vaccine. Dr June Raine, chief executive of the MHRA, said on Friday that for second doses the ratio had fallen to one in a million.
The death rate from rare blood clots was 20%.
In early April, the UK said people under 30 would be offered an alternative to the Oxford-AstraZeneca vaccine, which was approved for use in the country at the end of December.
Benefits vs Risks
Raine stressed during Friday’s press conference that the authority had not changed its approval of the AstraZeneca vaccine because the benefits continued to outweigh the risks for the vast majority of people.
“The balance of benefits and risks is very favorable for the older age groups, but it is more finely balanced for the younger ones,” she said.
According to the MHRA report – which was updated on Thursday – there had been a higher incidence of these blood clots in young adults. There were also more reports of blood clots occurring in women, although officials noted that this has not been seen in all age groups and “the difference remains small.”
An estimated 22.6 million first doses and 5.9 million second doses of the AstraZeneca Covid-19 vaccine had been administered in the UK until April 28.
Medicines regulatory authorities in the UK and EU identified possible links between the vaccine and rare blood clots last month. Officials at the European Medicines Agency said most cases had occurred in women under the age of 60 within two weeks of the vaccine.
The World Health Organization and the International Society of Thrombosis and Hemostasis have all said that the benefits of administering the Oxford-AstraZeneca vaccine continue to outweigh the risks.