LONDON – Britain said on Wednesday it would reduce the use of AstraZeneca’s vaccine in adults under the age of 30 due to the risk of rare blood clots, a blow to the efforts of dozens of countries dependent on the vaccine to eradicate the coronavirus pandemic worldwide surge in cases.
Adding to the unease, the European Medicines Agency described a ‘possible link’ between the vaccine and rare clots, although it said Covid-19 remained the far greater threat, leaving decisions on how to use the vaccine in the hands of the 27 Member States of the European Union.
Taken together, these decisions represented a considerable setback for the shooting of AstraZeneca, which was seen as the main weapon in the battle to reduce the number of deaths in the south of the planet from lack of vaccines.
The world’s most widely administered coronavirus vaccine, it’s much cheaper and easier to store than some of the alternatives, boosting its use in at least 111 countries, rich and poor. Britain-based AstraZeneca has pledged to deliver three billion doses this year, enough to inoculate nearly one in five people worldwide.
Britons under the age of 30 will receive another vaccine if it is available, with a few exceptions, officials said. Until Wednesday, Britain had not hesitated in its use of the local vaccine, holding out even as many European neighbors have halted injections due to unusual, albeit sometimes fatal, clots.
But cases have also started to appear in Britain, and a consensus has since emerged among global regulators that evidence points to a plausible, as yet unexplained, link between the vaccine and rare clots.
Amid a vicious wave of Covid-19 in Europe, security concerns have delayed vaccinations, undermined confidence in the shot and created a patchwork of different policies across the continent. The most devastating effects of the fear of security, however, could still fall on the poorest countries which depend entirely on AstraZeneca’s vaccine.
Concerns have arisen even though clots are extremely rare. As of Sunday, officials said, European regulators had received reports of 169 brain clots and 53 other clotting events, often associated with low platelets, among around 34 million people who received the AstraZeneca vaccine through Europe.
Britain has purchased enough vaccines from several manufacturers that the policy change on AstraZeneca does not significantly slow the pace of vaccinations. But other countries are starving for doses. Cameroon and the Democratic Republic of the Congo have already delayed injections of AstraZeneca’s vaccine amid growing concerns in Europe. Any further hesitation, scientists say, could cost lives.
“In developing countries, the dynamic is either to use the vaccine you have or to have nothing,” said Penny Ward, visiting professor of pharmaceutical medicine at King’s College London. “In this case, carnage ensues.”
For the vast majority of people, UK and EU regulators said on Wednesday, the benefits of AstraZeneca’s shot far outweigh the risks. Bleeding problems were occurring at a rate of about one in 100,000 recipients across Europe. Meanwhile, in Britain, the vaccine has reduced hospitalizations from Covid-19 – which in itself can cause serious bleeding problems – and saved thousands of lives, regulators said.
British health officials have estimated the risk of being admitted to an intensive care unit for Covid-19 outweighs the dangers of unusual blood clots in almost all age groups and at almost all levels of the epidemic.
But since younger people are less likely to develop severe Covid-19, regulators said, any vaccine given in this age group must cross a higher safety bar. UK data also suggests that young people are more prone to rare clots, making health officials there and in Europe more cautious about giving them the vaccine.
In response to new regulatory guidelines, Italy on Wednesday recommended not to administer the AstraZeneca vaccine to people under the age of 60. A number of countries, including Germany, France, Canada and the Netherlands, had already stopped using it among younger people, setting the age limit. at 55 or 60 years old. Norway and Denmark completely stopped shooting while they investigated.
“The balance between benefits and risks is very favorable for older people, but it is more finely balanced for younger people,” said Dr June Raine, Britain’s leading drug regulator.
Blood clots have raised increased concern due to their unusual constellation of factors: blockages in the major veins, often the ones that drain blood from the brain, combined with a low platelet count.
The emergence of cases in early March presented countries with one of their most serious regulatory tests since the injections were first administered. As millions of people were vaccinated, problems would inevitably arise, too rare to show up in clinical trials involving thousands of people.
But while scientists have pleaded for coordinated action, health officials across Europe have defied the recommendations of the European Medicines Agency and suspended injections of the AstraZeneca vaccine. Most resumed firing a few days later.
Some pundits said the breaks were understandable, but the about-face was disorienting, especially amid a nasty row between EU lawmakers and AstraZeneca over drastic supply cuts that prompted some executives policies to wrongly denigrate the vaccine. Surveys have started to show that in Germany, France and Spain, most people doubted vaccine safety.
Overall, vaccine use has suffered: Across Europe, 64% of administered doses of AstraZeneca vaccine were injected into people’s arms, significantly lower than rates for other injections.
“We were hoping there would have been collaboration, and more discussion, between regulators, instead of a lot of different countries going in all kinds of directions,” Professor Ward said. “This aspect has really been the most unnecessary.”
As doctors across Europe have investigated the rare blood clots, they have become increasingly convinced of a link, however poorly understood, to the vaccine.
The inoculation appears to trigger an immune response targeting platelets in a small number of people, according to doctors and regulators. The platelets, in turn, caused dangerous clots in different parts of the body, including the brain, in some cases leading to a rare type of stroke.
But why some people generated antibodies targeting platelets is not known, the doctors said. Some components of the vaccine or an overreaction of the immune system in some recipients – or both – could be the cause. No pre-existing condition is known to make patients more vulnerable.
More women than men suffered from these bleeding problems, but UK regulators said it appeared to be the result of women being vaccinated in greater numbers due to their frontline medical roles.
Regulators have asked vaccines and doctors to watch for certain symptoms, including severe and persistent headaches and tiny spots of blood under the skin. Groups of doctors have disseminated advice on how to treat the disorder.
As of March 22, regulators had carried out a detailed examination of 86 cases, including 18 fatalities, they said.
Concerns about the shooting became acute enough in Britain this week that the University of Oxford, which developed the vaccine with AstraZeneca, stopped giving doses in a two-month trial in children .
“Safety has been our priority throughout vaccine development,” said Andrew Pollard, the Oxford researcher in charge of the trials, on Wednesday. The identification of the clots, he added, “shows that the security system is working.”
In the United States, AstraZeneca is preparing to apply for emergency use authorization from the Food and Drug Administration. If and when they accept the request, regulators at that agency are supposed to review cases of coagulation.
The United States, brimming with vaccines from three other manufacturers, may not ultimately need AstraZeneca’s vaccine. But any decision by the FDA should carry considerable weight in some of the poorer countries that count on the spot.
The World Health Organization said a subcommittee on vaccine safety met on Wednesday and noted that “rare adverse events following vaccination should be weighed against the risk of death from Covid-19 disease and the potential of vaccines to prevent infections ”. He said a link to the bleeding problems, while “plausible”, had not been confirmed.
For Britain, the AstraZeneca vaccine has become a huge source of national pride and the backbone of the country’s rapid vaccination program.
Even though young people are less exposed to severe Covid-19, scientists said, their inoculation remains essential to create sufficient protection for the population to end the pandemic.
Emma Bubola, Monika Pronczuk and Rebecca Robbins contributed reporting.