AstraZeneca‘s share price has slumped by one per cent after UK health chiefs said Britons under 30 should not take its vaccine.
The British-Swedish pharmaceutical firm, based in Cambridge, was trading at 7.110 points on Tuesday morning.
But it dipped down to 7.107 at 8am before a sharp rise back up to 7.139 within 20 minutes.
It continued to fluctuate throughout the morning and early afternoon – straying from 7.160 at 9.47am to a lunchtime low of 7.121.
Yet the stocks took their biggest hit just after 3.30pm when it was announced the jabs should not be used on people under 30.
The share price nosedived back down to 7.110 points at 3.40pm before staying steady at 7.111 when the markets closed at 4.30pm.
Despite the news, the UK medicines watchdog said the benefits of the Oxford/AstraZeneca vaccine continue to outweigh any risks for most people.
European regulators ruled that unusual blood clots that have hit headlines in the past week were ‘very rare side effects’ of the jab.
The Medicines and Healthcare products Regulatory Agency said there were still huge benefits of the vaccine in preventing Covid-19, and has not concluded it causes rare clots, although it says the link is getting firmer.
Due to a very small number of blood clots in younger people and a changing risk/benefit, those under the age of 30 will be offered Pfizer or Moderna instead of the AstraZeneca jab.
Dr June Raine, chief executive of the MHRA, told a briefing that the clots were ‘extremely rare’.
She added: ‘Based on the current evidence, the benefits of the Covid-19 vaccine AstraZeneca against Covid-19 and its associated risks – hospitalisation and death – continues to outweigh the risks for the vast majority of people.
‘Our review has reinforced that the risk of this rare suspected side effect remains extremely small.’
But she added: ‘The evidence is firming up and our review has concluded that while it’s a strong possibility, more work is needed to establish beyond all doubt that the vaccine has caused these side effects.’
Professor Wei Shen, chairman of the Joint Committee on Vaccination and Immunisation, said the recommendation to prefer other vaccines to AstraZeneca for the under-30s was ‘out of the utmost caution’ rather than because of ‘any serious safety concerns’.
Meanwhile, Professor Sir Munir Pirmohamed, chairman of the Commission on Human Medicines, said any risks from the jab had to be set against the fact that around 30% of people with Covid suffer low blood platelet counts, while Covid also ’causes clotting’.
Some 7.8 per cent of people with Covid suffer blood clots on the lungs, while 11.2 per cent will suffer deep vein thrombosis (DVT), he added.
England’s deputy chief medical officer Professor Jonathan Van-Tam used a nautical analogy to describe the ‘course correction’ in the vaccination programme.
He told the briefing it was ‘quite normal’ for medics to alter their preferences on how to treat patients.
He said changes were made to the flu vaccine programme a few years ago and ‘changes in preference for vaccines are business as usual’.
He added: ‘This is a massive beast that we are driving along at enormous pace with enormous success, this vaccine programme.
‘If you sail a massive liner across the Atlantic then it’s not really reasonable that you aren’t going to have to make at least one course correction during that voyage.’
He acknowledged the change in recommended use of the AstraZeneca vaccine might result in delays and longer journeys to receive the jab.
A review by the European Medicines Agency’s (EMA) safety committee concluded on Wednesday that ‘unusual blood clots with low blood platelets should be listed as very rare side effects’ of the Oxford/AstraZeneca vaccine.
Emer Cooke, executive director of the EMA, said its review ‘confirmed that the benefits of the AstraZeneca vaccine in preventing Covid-19 overall outweigh the risk of side effects’, adding: ‘Vaccination is extremely important in helping us in the fight against Covid-19.’
Dr Sabine Straus, safety committee chairwoman at the EMA, said: ‘This vaccine has proven to be highly effective, it prevents severe disease and hospitalisation and it is saving lives.
‘Vaccination is extremely important in helping us in the fight against Covid-19 and we need to use the vaccines we have to protect us from the devastating effects.’
In the UK, the MHRA said that those who have had their first dose of the AstraZeneca vaccine should still get their second dose.
Only those who suffered a rare blood clot after the first dose should not get vaccinated.
Anyone with blood disorders that leave them at risk of clotting should discuss the benefits and risks of vaccination with their doctor before going for a jab.
Up to March 31, the MHRA had 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 millions of doses given.
Of these 79, a total of 19 people had died, although it has not been established what the cause was in every case.
The 79 cases occurred in 51 women and 28 men, aged from 18 to 79. Of the 19 who died, three were under the age of 30, the MHRA said.
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.
The other five cases were other kinds of thrombosis in major veins.
The MHRA has concluded that the balance of risk for the vaccine is very favourable for older people but ‘more finely balanced’ for younger groups.
Meanwhile, in Europe, the EMA has carried out an in-depth review of 62 cases of CVST and 24 cases of splanchnic vein thrombosis in which 18 people died.
Ms Cooke, from the EMA, defended the decision not to follow the UK in recommending that those under the age of 30 be offered another vaccine.
She said the available data did not allow the EMA to draw any causal link with age groups, or whether male or female.
She said: ‘There is a lot more use in younger age groups in the UK than there is in the EU at the moment and we will take this into account in our further evaluations.’
Prime Minister Boris Johnson said the Government believed the Oxford/AstraZeneca vaccine was ‘safe’, telling reporters on a visit to Cornwall: ‘But the crucial thing for everybody is to listen to what the scientists, the medical experts have to say later on today.’
On the vaccination programme, he added: ‘You can really start to see some of the benefits of that – it’s pretty clear that the decline in the number of deaths, the decline in the number of hospitalisations is being fuelled, is being assisted, the steepness of that decline is being helped, by the rollout of the vaccines so it’s very important for everybody to continue to get your second jab when you’re asked to come forward for your turn.’
More than 20 million doses of the AstraZeneca vaccine have now been given in the UK, saving an estimated 6,000 lives.