Matt Hancock and chief scientists are seeking to maintain public confidence in the Oxford/AstraZeneca vaccine after regulators pointed to a one in a million chance of dying from a rare blood clot.

The Health Secretary said everyone should take a vaccine when their time comes, and the risk of experiencing a brain clot was the same as “taking a long-haul flight”.

He urged the under-30s, who will be offered an alternative vaccine to AstraZeneca, to take a jab to protect loved ones and avoid the risk of long Covid, adding there were was “more than enough” Moderna and Pfizer for this age range.

In a round of broadcast interviews, Mr Hancock said vaccines are clearly breaking the link between Covid cases and deaths in the UK and were saving “thousands of lives”.

He told Sky News: “The number of people dying from Covid halved in the last nine days… and is down 90% from the peak.”

All vaccines in use in the UK were “safe for all ages”, but the “extremely rare” risk of suffering a rare brain blood clot, and the tipping of the balance of risk for the under-30s, means they could be given other jabs instead.

Speaking directly to younger people who may be thinking they do not need a vaccine, Mr Hancock told BBC Breakfast: “The vaccines are safe, and if you want to have the Pfizer vaccine or Moderna vaccine instead then that is fine.

“Covid is a horrible disease and long Covid affects people in their 20s just as much it seems as any other age group and can have debilitating side effects that essentially ruin your life.”

Weekly rate of new Covid-19 cases in the UK
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He added: “The safety system that we have around this vaccine is so sensitive that it can pick up events that are four in a million (the chance of developing a rare brain blood clot) – I’m told this is about the equivalent risk of taking a long-haul flight.”

Mr Hancock said there were almost 10.2 million people aged 18 to 29 in the UK, of whom 1.6 million have had their first vaccine.

Professor Jeremy Brown, a member of the Joint Committee on Vaccination and Immunisation (JCVI), said that the benefit of vaccinating young people is not just preventing severe disease.

He told Sky News: “It actually will prevent them catching Covid, and if they don’t get Covid then the chance of developing so-called long Covid – the symptoms you get which many people get, about 10%, after they’ve had even a very mild infection – that will prevent that.

Potential benefits/harms of AstraZeneca Covid-19 vaccine: high exposure scenario
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“It also allows younger people to visit their relatives who are elderly and more vulnerable to the disease, without the risk of infecting them.

“Lastly, there are social benefits which have been much discussed over the past few days – travel, for example. I think it’s unlikely that people will be allowed to travel out of the country easily unless they have been vaccinated.”

Meanwhile, Professor Anthony Harnden, deputy chairman of the JCVI, explained that the chance of suffering a clot after a vaccine was much lower than for other medicines or during pregnancy.

“These are extremely rare events – much, much more rare than, for instance, clots due to common drugs that we prescribe such as the contraceptive pill; much rarer than clots during pregnancy; much, much rarer than clots due to Covid itself,” he told BBC Breakfast.

“We still feel this is a safe and effective vaccine where the benefits far outweigh the risks for the majority of people.

“In many ways, it’s better to know the known than the unknown, so I would encourage anybody who’s been offered either their first dose of the Oxford/AstraZeneca vaccine, and certainly their second dose, when there’s been no cases (of clots) for second doses, to receive it when offered.”

Prof Harnden insisted “the vaccination programme is going full steam ahead” across the UK and “everybody should remain confident in it”.

The risks of Covid and severe illness were highest in older age groups, but when you look down to very young people, “the risks aren’t quite as high”, he said.

Adults who have received Covid-19 vaccine
(PA Graphics)

This meant that the risk of dying from Covid or a clot after a vaccine looked like they might be more similar for young people.

Urging anyone who has had one dose of AstraZeneca to have their second, Prof Harnden said “we don’t know how long that protection is going to last for, and it could well drop off”.

He continued: “We do know that as we come out of lockdown and as cases in Europe rise during a third wave, we may experience a third wave in this country over the next few months.

“And therefore to be unprotected would be to leave yourself at risk of developing Covid, and of course all the complications that come with Covid, including I might say quite severe blood clots, much higher risk of getting severe blood clots from Covid than the extremely small risk from this vaccination.”

Professor Andrew Pollard, director of the Oxford Vaccine Group, said he had woken up on Thursday worrying about the pandemic and how many people are still dying.

He told BBC Radio 4’s Today programme: “What I did wake up this morning worrying about is the pandemic.

“It’s not over, it really does continue to threaten the whole of humanity – today about 12,000 people around the world will be confirmed dead as a result of coronavirus.

“And those numbers are getting worse – in Europe, in our immediate neighbours, in South Asia, in Latin America – and so this really is not the time to waver.

“We just need to put our confidence in the hands of the system which I think really has had a big boost by their ability to pick up an incredibly rare event through the monitoring that’s going on, and that really gives me confidence that we can continue with the programme.”

Meanwhile, Professor Beverley Hunt, an expert in thrombosis and haemostasis at King’s College London, who has been working with the Medicines and Healthcare products Regulatory Agency (MHRA) on the clot cases, said those affected had been presenting to doctors “with the worst headache they’ve ever had” four days after vaccination and sometimes later, though prompt treatment could save lives.

On Wednesday, the MHRA said the benefits of the vaccine still outweigh the risks overall.

While it has not concluded that the vaccine causes rare brain clots, it says the link is getting firmer.

Up to March 31, the MHRA in the UK has received 79 reports of blood clots accompanied by low blood platelet count, all in people who had their first dose of the vaccine, out of around 20 million doses given.

Of these 79, a total of 19 people have died, with three under the age of 30.