Following a “rigorous scientific review of all the available data”, the evidence shows that blood clots in veins are not linked to the AstraZeneca Covid-19 vaccine, the Medicines and Healthcare products Regulatory Agency (MHRA) has announced.

However, as a precautionary measure, the MHRA is advising those experiencing specific side effects following the vaccine to seek medical attention.

This is what you need to know.

‘Seek medical attention’

Dr June Raine, MHRA Chief Executive, said: “While we continue to investigate these cases [of blood clots], as a precautionary measure we would advise anyone with a headache that lasts for more than four days after vaccination, or bruising beyond the site of vaccination after a few days, to seek medical attention.

“However, please remember that mild flu-like symptoms remain one of the most common side effects of any Covid-19 vaccine, including headache, chills and fever. These generally appear within a few hours and resolve within a day or two, but not everyone gets them.

“We will continue to robustly monitor all the data we have on this extremely rare possible side effect.”

‘No evidence of blood clot link’

Dr Raine said: “We continually monitor safety during use of all vaccines to protect the public, and to ensure the benefits continue to outweigh the risks.

“Our thorough and careful review, alongside the critical assessment of leading, independent scientists, shows that there is no evidence that blood clots in veins is occurring more than would be expected in the absence of vaccination, for either vaccine.

“We have received a very small number of reports of an extremely rare form of blood clot in the cerebral veins (sinus vein thrombosis, or CSVT) occurring together with lowered platelets soon after vaccination. This type of blood clot can occur naturally in people who have not been vaccinated as well as in those suffering from Covid-19.

“Given the extremely rare rate of occurrence of these CSVT events among the 11 million people vaccinated, and as a link to the vaccine is unproven, the benefits of the vaccine in preventing Covid-19, with its associated risk of hospitalisation and death, continue to outweigh the risks of potential side effects.

“You should therefore continue to get your jab when it is your turn.”

Boris Johnson to receive AstraZeneca vaccine

Prime Minister Boris Johnson is set to receive his first dose of the AstraZeneca vaccine today (Friday 19 March).

Speaking to a Downing Street press conference, Johnson said: “The Oxford/AstraZeneca jab is safe, and the Pfizer jab is safe.

“The thing that isn’t safe is catching Covid, which is why it is so important that we all get our jabs as soon as our turn comes.”

A number of countries, including Germany, France and Italy, had chosen to temporarily pause the rollout of the AstraZeneca vaccine until an investigation had been conducted into the vaccine's safety, and any potential links between blood clots.

The European Medicines Agency (EMA) has now called the vaccine “safe and effective”, with those countries now reinstating the use of the jab.