Germany, France and Italy said on Monday they would suspend AstraZeneca Covid-19 shots after several countries reported possible serious side-effects, but the World Health Organization (WHO) said there was no proven link and people should not panic.
Still, the decision by the European Union's three biggest countries to put inoculations with the AstraZeneca shot on hold threw the already struggling vaccination campaign in the 27-nation EU into disarray.
Denmark and Norway stopped giving the shot last week after reporting isolated cases of bleeding, blood clots and a low platelet count. Iceland and Bulgaria followed suit and Ireland and the Netherlands announced suspensions on Sunday.
Spain will stop using the vaccine for at least 15 days, Cadena Ser radio reported, citing unnamed sources.
The top WHO scientist reiterated on Monday that there have been no documented deaths linked to Covid-19 vaccines.
"We do not want people to panic," Soumya Swaminathan said on a virtual media briefing, adding there has been no association, so far, pinpointed between so-called "thromboembolic events" reported in some countries and Covid-19 shots.
WHO chief Tedros Adhanom Ghebreyesus said an advisory committee meeting on AstraZeneca would be held on Tuesday. EU medicines regulator EMA will also convene this week to assess the information gathered into whether the AstraZeneca shot contributed to thromboembolic events in those inoculated.
The moves by some of Europe's largest and most populous countries will deepen concerns about the slow rollout of vaccines in the region, which has been plagued by shortages due to problems producing vaccines, including AstraZeneca's.
Germany warned last week it was facing a third wave of infections, Italy is intensifying lockdowns and hospitals in the Paris region are close to being overloaded.
German Health Minister Jens Spahn said that although the risk of blood clots was low, it could not be ruled out.
"This is a professional decision, not a political one," Spahn said, adding he was following a recommendation of the Paul Ehrlich Institute, Germany's vaccine regulator.
France said it was suspending the vaccine's use pending an assessment by EMA.
"The decision taken, in conformity also with our European policy, is to suspend, out of precaution, vaccination with the AZ shot, hoping that we can resume quickly if the EMA's guidance allows," French President Emmanuel Macron said.
Italy said its halt was a "precautionary and temporary measure" pending EMA's ruling.
"The EMA will meet soon to clarify any doubts so that the AstraZeneca vaccine can be resumed safely in the vaccination campaign as soon as possible," said Gianni Rezza, Director General of Prevention at Italy's Ministry of Health.
Austria and Spain have stopped using particular batches and prosecutors in the northern Italian region of Piedmont earlier seized 393,600 doses following the death of a man hours after he was vaccinated. It was the second region to do so after Sicily, where two people had died shortly after having their shots.
The WHO appealed to countries not to suspend vaccinations against a disease that has caused more than 2.7 million deaths worldwide. WHO Director-General Tedros said systems were in place to protect public health.
"This does not necessarily mean these events are linked to Covid-19 vaccination, but it's routine practice to investigate them, and it shows that the surveillance system works and that effective controls are in place," he told the media briefing.
The United Kingdom said it had no concerns, while Poland said it thought the benefits outweighed any risks.
The EMA has said that as of March 10, a total of 30 cases of blood clotting had been reported among close to 5 million people vaccinated with the AstraZeneca shot in the European Economic Area, which links 30 European countries.
Michael Head, a senior research fellow in global health at the University of Southampton, said the decisions by France, Germany and others looked baffling.
"The data we have suggests that numbers of adverse events related to blood clots are the same (and possibly, in fact lower) in vaccinated groups compared to unvaccinated populations," he said, adding that halting a vaccination programme had consequences.
"This results in delays in protecting people, and the potential for increased vaccine hesitancy, as a result of people who have seen the headlines and understandably become concerned. There are no signs yet of any data that really justify these decisions."
A senior German infectious diseases physician, however, said the background incidence of 2-5 thromboses per million per year was significantly lower than the number of 7 out of 1.6 million vaccinated people cited by Germany's health ministry.
"This should be the reason to suspend the vaccination in Germany until all cases, including suspected cases in Germany and Europe, have been completely cleared up," said Clemens Wendtner, head of the special unit for highly contagious life threatening infections at the Schwabing Clinic in Munich.
AstraZeneca's shot was among the first and cheapest to be developed and launched at volume since the coronavirus was first identified in central China at the end of 2019, and is set to be the mainstay of vaccination programmes in much of the developing world.
Thailand announced plans on Monday to go ahead with the Anglo-Swedish firm's shot after suspending its use on Friday, but Indonesia said it would wait for the WHO to report.
The WHO said its advisory panel was reviewing reports related to the shot and would release its findings as soon as possible. But it said it was unlikely to change its recommendations, issued last month, for widespread use, including in countries where the South African variant of the virus may reduce its efficacy.
The EMA has also said there was no indication the events were caused by the vaccination and that the number of reported blood clots was no higher than seen in the general population.
But the handful of reported side-effects in Europe have upset vaccination programmes already stumbling over slow rollouts and vaccine scepticism in some countries.
The Netherlands said on Monday it had seen 10 cases of possible noteworthy adverse side-effects from the AstraZeneca shot, hours after putting its vaccination programme on hold following reports of potential side-effects in other countries.
Recent information indicates "a very special, rarely occurring form of thrombosis, of which some cases appear to have occurred shortly after vaccination. This is of course suspicious and should be investigated," said Anke Huckriede, vaccinology professor at the University of Groningen in the Netherlands.
Denmark reported "highly unusual" symptoms in a 60-year-old citizen who died from a blood clot after receiving the vaccine, the same phrase used on Saturday by Norway about three people under the age of 50 it said were being treated in hospital.
One of the three health workers hospitalised in Norway after receiving the AstraZeneca shot had died, health authorities said on Monday, but there was no evidence the vaccine was the cause.
AstraZeneca said earlier it had conducted a review covering more than 17 million people vaccinated in the EU and the UK which had shown no evidence of an increased risk of blood clots.
Long-awaited results from AstraZeneca's 30,000-person US vaccine trial are now being reviewed by independent monitors to determine whether the shot is safe and effective, a top US official said on Monday.