How long after AstraZeneca vaccine have blood clots appeared? MHRA issues new guidance on rare possible side effect

Health officials and chief scientists are seeking to maintain public confidence in the AstraZeneca Covid-19 vaccine, due to a potential link with blood clots.

The Medicines and Healthcare products Regulatory Agency (MHRA) has not yet concluded that the “extremely rare” blood clots in the brain are caused by the jab, and pointed to a one in a million chance of dying from a rare blood clot.

Health Secretary Matt Hancock has said that everyone should take a coronavirus vaccine when their time comes, added that the risk of experiencing a brain clot was the same as “taking a long-haul flight”.

Young adults under the age of 30 will now be offered an alternative vaccine to AstraZeneca as investigations continue, with Mr Hancock stating there was “more than enough” Moderna and Pfizer jabs for this age range.

Here’s what is known about the blood clot reports so far, and the side effects you need to look for if you are given the AstraZeneca vaccine.

How long after the vaccine have blood clots been reported?

A total of 79 cases of blood clots accompanied by low blood platelet count have been reported in the UK up to 31 March, according to the MHRA.

Neil Astles, 59, is the first person to be named in the UK who is suspected to have died from side effects linked to the AstraZeneca Vaccine.

Mr Astles, a solicitor at Warrington Borough Council, became ill on 17 March and later died in hospital on Easter Sunday (4 April) from a blood clot on the brain, The Telegraph reports.

His sister Alison, who works as a pharmacist, explained that he began to suffer with headaches and nausea around a week after having the vaccine, along with loss of vision.

He was taken to the emergency department of the Royal Liverpool University Hospital on Friday (3 April) night where doctors found a “huge blood clot” and he died two days later.

However, Dr Astles has urged people to continue getting vaccinated, saying that her brother was “extraordinarily unlucky”.

In all of the 79 cases that have been reported, the blood clots occurred in people who had received their first vaccine dose, out of around 20 million doses given.

A total of 19 people from these 79 later died, although it has not been confirmed what the cause of death was in every case.

Blood clots occurred in 51 women and 28 men, aged from 18 to 79, and of the 19 who died, three of these were under the age of 30.

Some 14 cases of the 19 were cerebral venous sinus thrombosis (CVST), a specific type of clot that prevents blood from draining from the brain, while the other five were other kinds of thrombosis in major veins.

What side effects should I look for?

The MHRA has confirmed that the evidence to date does not suggest that the AstraZeneca Covid-19 vaccine causes venous thromboembolism without a low platelet count, and notes that this type of blood clot, together with lowered platelets, can rarely occur naturally in unvaccinated people as well as in people with Covid-19.

While investigations continue, the MHRA is advising as a precautionary measure that anyone who experiences symptoms four days or more after vaccination should seek medical advice.

These symptoms may include:

- a new onset of severe or persistent headache, blurred vision, confusion or seizures

- develop shortness of breath, chest pain, leg swelling or persistent abdominal pain,

- unusual skin bruising or pinpoint round spots beyond the injection site

People who are at higher risk of blood clots because of their medical condition should only be considered for the AstraZeneca vaccine if the benefits from the protection against Covid-19 outweighs the potential risks.

Anyone who experienced cerebral or other major blood clots occurring with low levels of platelets after their first vaccine AstraZeneca dose should not have their second jab.

Anyone who did not experience any of the above side effects should come forward for their second dose when invited.

Women who are pregnant should discuss with their healthcare professional whether the benefits of having the vaccine outweigh the risks for them.

Dr June Raine, MHRA chief executive, said: “No effective medicine or vaccine is without risk.

“We continually monitor safety during widespread use of any vaccine. This is to ensure vaccines are performing as expected, to identify any new side effects that may arise, and to ensure the benefits continue to outweigh the risks.

“The public’s safety is always at the forefront of our minds and we take every report of a suspected side effect very seriously indeed. We thoroughly analyse each and every report as we receive it and although the number of reports of CVST and other thromboembolic events has increased over the last week, so has the overall number of vaccinations administered, therefore these blood clots remain extremely rare and unlikely to occur.

“We ask anyone who suspects they have experienced a side effect linked with their COVID-19 vaccine to report it to the Coronavirus Yellow Card website.

“It is still vitally important that people come forward for their vaccination when invited to do so.”