Johnson and Johnson vaccine: what we know about blood clot link - and how it will impact the UK rollout

The UK government remains confident that it will hit its target of offering a jab to all adults by the end of July

The US has paused the use of the J&J vaccine (Getty Images)

Johnson & Johnson confirmed it will delay rollout of its single-dose vaccine across Europe after the US paused the administration of the jab to investigate six cases of potentially dangerous blood clots seen in 6.8 million people vaccinated.

Regulators in the UK said that they will examine “any safety reports” during their considerations on whether or not to approve the jab.

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More than 6.8 million doses of the J&J vaccine have been administered in the US, the vast majority with no or mild side effects.

Here's what we know about the potential link between the vaccine and blood clots.

Why has the rollout been paused?

In a joint statement, the US Centres for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) said they were investigating clots in six women aged 18-48 that occurred six to 13 days after vaccination.

The clots occurred in veins that drain blood from the brain and occurred together with low platelets.

More than 6.8 million doses of the J&J vaccine have been administered in the US, the vast majority with no or mild side effects.

Dr Peter English, a past chairman of the British Medical Association’s public health medicine committee, said: “This would appear to be a highly precautionary move by the US agencies.

“According to reports to date, there appear to have been six cases of central venous sinus thrombosis (CVST), in over 6.8 million doses of vaccine given.

“Even if all of the cases were caused by the vaccine, the risk of less than one in a million would have to be set against the benefits of protection from Covid-19 disease – a disease which, in itself, causes clotting in many cases.

How will this effect the UK’s rollout?

The UK has 30 million doses of the inoculation on order, but it has not yet been signed off for use by the Medicines and Healthcare products Regulatory Agency (MHRA).

The doses are expected to arrive in the second half of 2021 if approved by the regulator.

But the Department of Health and Social Care (DHSC) insisted Johnson & Johnson’s decision to delay the rollout of its vaccine in Europe would not derail the UK’s programme to offer a jab to all adults by the end of July.

A DHSC spokesperson said: “Our vaccination programme continues to make phenomenal progress – with over 40 million vaccines administered so far.

“We have hit our target to offer a vaccine to everyone in phase one of the vaccination programme and we are on track to offer a jab to all adults by the end of July.”

The MHRA’s director of licensing Dr Siu Ping Lam added: “No vaccine would be authorised for use in the UK unless the expected high standards of safety, quality and effectiveness have been met.

“Vaccine safety is of paramount importance and we will monitor and evaluate any safety reports received promptly and robustly before a decision is made, working and sharing safety data with international regulators as necessary.”

What has the government said?

Downing Street said it would not “prejudge” the MHRA’s decision on the safety of the jab.

The Prime Minister’s spokesman said: “On Johnson & Johnson, it’s for the MHRA to make a ruling – obviously they are independent so I’m not going to prejudge their decision.

“It’s right that the independent safety watchdog looks at this and gives a ruling.”