As ministers and health chiefs stepped up a campaign to reassure the public about the safety of the vaccine, Professor Adam Finn explained that swift action could stop many of these cases of thrombosis becoming fatal.
“There is effective treatment for this condition,” said Professor Finn, a member of the Joint Committee on Vaccination and Immunisation and head of the Bristol Children’s Vaccine Centre.
“If it is provided promptly and correctly, we would expect to be able to avoid these deaths which have been occurring.”
He added: “Correct treatment should make a big difference and let’s be hopeful that we could prevent them entirely, but if not entirely then mostly.”
The Medicines and Healthcare products Regulatory Agency said that as a “precautionary measure” anyone who has certain symptoms four days or more after receiving the AstraZeneca vaccination is advised to seek prompt medical advice.
They are a new onset of severe or persistent headache, blurred vision, confusion or seizures, shortness of breath, chest pain, leg swelling, persistent abdominal pain, unusual skin bruising or pinpoint round spots beyond the injection site.
In a round of media interviews this morning, Matt Hancock sought to maintain public confidence in the AstraZeneca vaccine after regulators pointed to a one in a million chance of dying from a rare blood clot.
The Health Secretary urged on Sky News: “When you get the call, get the jab.”
He added that the risk of experiencing a brain clot linked to the vaccine, but not yet confirmed, was around the same as getting a clot from “taking a long-haul flight”.
The Joint Committee on Vaccination (JCVI) recommended using a different vaccine for the under-thirties, though the UK and EU medicine regulators said it could still be used for this younger age group.
The Medicines and Healthcare products Regulatory Agency (MHRA) said the benefits still outweighed the risks overall but while it has not concluded that the vaccine caused rare blood clots, it said the link was getting firmer.
Mr Hancock urged the under-thirties, 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 plentiful supplies of Moderna and Pfizer for this age group.
Out of just over 10 million people aged 18 to 29 in the UK, 1.6 million have had their first vaccine.
Women who are pregnant and people with blood disorders that mean they are at risk of clotting should discuss the benefits and risks of vaccination with their doctor before getting the jab.
Professor Beverley Hunt, an expert in thrombosis and haemostasis at King’s College London, who has been working with the MHRA on the clot cases, said people had been presenting to doctors “with the worst headache they’ve ever had” four days after vaccination and sometimes later.
She also stated that early treatment could improve outcomes. Professor Andrew Pollard, director of the Oxford vaccine group, said “this is not the time to waver” over the rare blood clots linked to the roll-out of the AstraZeneca vaccine because coronavirus cases were rising in Europe and other nations around the world.
He told BBC Radio 4’s Today programme: “We have brilliant haematologists here in the NHS who are looking out for any patients to make sure they get the best possible treatment, which is being worked out by them if one of these very rare cases were to happen.”
He added that there have not been any cases of blood clots associated with second AstraZeneca doses. In other developments:
Professor Anthony Harnden, deputy chair of the JCVI, said his “strong advice” is for people who have had the first AstraZeneca dose to get their second one, because it is not known how long protection from a first dose lasts.
The family of Neil Astles, 59, who died in hospital on Sunday after receiving his first AstraZeneca jab dose on March 17, said they wanted the public to continue taking up the vaccine.
Mr Hancock said people who have had a first dose would not be able to choose to have a different second one as such usage had not yet been properly researched.
The Health Secretary defended the speed of easing restrictions after experts at University College London claimed the UK is expected to have passed the threshold for herd immunity by Monday, the day pubs will be able to offer outside service and non-essential shops reopen.
The MHRA said that up to March 31, across the UK, it had received 79 reports of blood clots accompanied by low blood platelet count,all in people who had their first dose of the Oxford vaccine, out of around 20 million doses. Of these 79, a total of 19 had died, although it has not been established what the cause was in every case.
Of the 19 who died, three were under 30.
A separate review by the European Medicines Agency concluded yesterday that “unusual blood clots with low blood platelets should be listed as very rare side effects” of the AstraZeneca vaccine.