Shares in AstraZeneca fell as the UK reported 25 new cases of rare blood clots possibly linked to the British-produced Covid-19 vaccine, while shares of its main European rival, BioNTech, climbed sharply in Frankfurt trade.
Britain's Medicines and Healthcare Products Regulatory Agency said that the latest reports mean that the total number of blood clot cases has risen to 30, but again said that the benefits of using the vaccine far outweighed the risks.
AstraZeneca has been at the centre of a political storm between Britain and the EU.
The UK government, led by Boris Johnson, is relying on AstraZeneca, which was developed by Oxford University, to vaccinate a large share of the population, in a race to lift the Covid restrictions and open the economy.
In contrast, EU president Ursula von der Leyen has accused AstraZeneca of failing to meet the terms of its contract to deliver supplies promised in its last autumn contract that has led to shortages of supply across Europe, including in Ireland. The EU has threatened to use its powers to restrict vaccine exports.
The UK — where about half the population has got at least one jab — and the US are racing ahead with their vaccination programmes, while a number of European countries, including France, have been forced to extend their lockdowns as the number of Covid cases and hospitalisations rise in recent days.
Economists say that the economic hits to the eurozone economy will be deeper as a result of the comparatively slow rollout of the vaccine programmes in the EU.
The significance of the new blood clot reports is that while the rate of incidents following the AstraZeneca shot in the UK is about one in 600,000, there are no reports of the same reactions to the vaccine from BioNTech-Pfizer, which is also being used in Britain.
Shares in AstraZeneca fell 1%, which means that the gains for the company have been pared back to only 5.5% in the past year. The stock market values AstraZeneca at €110.5bn.
In contrast, shares in BioNTech, the German company founded by a husband and wife team and which developed the vaccine with the US drugs giant Pfizer, climbed 4% in Frankfurt trade.
Its shares have risen 90% from a year ago, to value the firm at €23.3bn.
Shares in other vaccine makers which are slated to play an important part in Ireland's vaccination programme later this year also rose on Friday.
Moderna rose by over 1% to value the US vaccine maker at €45.2bn. Its shares have soared 300% from April last year.
Shares in Pfizer, which is one of the largest diversified drug makers in the world, were little changed.
Its shares have risen 21% in the past year, to value the firm at €172.3bn.
“On the basis of this ongoing review, the benefits of the vaccines against Covid-19 continue to outweigh any risks and you should continue to get your vaccine when invited to do so,” said Britain's Medicines and Healthcare Products Regulatory Agency.
The AstraZeneca and the BioNTech-Pfizer vaccines have shown “very high levels of protection” against Covid-19, the agency said, adding that “all vaccines and medicines have some side effects”.
Earlier this week, the EU drugs regulator said a link between the AstraZeneca vaccine and a rare type of blood clot is possible, identifying at least 62 cases of the condition. The European Medicines Agency said its safety committee will probably issue an updated recommendation next week.
Germany has restricted younger people from taking the AstraZeneca vaccine. That followed reports of 31 cases of the rare clots, mostly in women. Norway and Denmark extended suspensions on the use of the shot.
On Friday, Australia reported one case of clotting disorders following inoculation with the AstraZeneca vaccine and is investigating.
- Additional reporting, Bloomberg