LONDON – Britain said on Wednesday it would slow down the use of the AstraZeneca vaccine in adults under the age of 30 due to the risk of rare blood clots, a blow to the efforts of many countries that depend on the vaccine to eradicate the coronavirus pandemic in the midst of a global increase in cases.
To increase the unrest, the European Medicines Agency outlined a “possible link” between the vaccine and rare blood clots, although it said that Covid-19 remained the much bigger threat, leaving decisions on how to use the vaccine in the hands of the 27 Member States in the European Union. European Union.
The world’s most administered coronavirus vaccine, it is far cheaper and easier to store than some of the alternatives, encouraging use in at least 111 countries, rich and poor. AstraZeneca, based in the UK, has promised to deliver three billion doses this year, enough to inoculate almost one in five people worldwide.
Britons under the age of 30 will receive another vaccine, if one is available, with limited exceptions, officials said. Until Wednesday, Britain had not wavered in the use of the homemade vaccine and persevered, although many European neighbors stopped injections over the unusual, but sometimes fatal, blood clots.
But cases also began to emerge in the UK, and there has since been a consensus among global regulators that the evidence points to a probable, yet unexplained link between the vaccine and rare blood clots.
In the midst of a vicious wave of Covid-19 in Europe, security concerns have delayed vaccinations, lowered confidence in the shot and created a patchwork of different policies across the continent. However, the most devastating effects of the safety scare may still fall on poorer nations that are completely dependent on AstraZeneca’s vaccine.
The concerns have arisen, although blood clots are very rare. As of Sunday, officials said European regulators had received reports of 169 blood clots in the brain and 53 other coagulation events, often combined with low platelets, among about 34 million people who had received the AstraZeneca vaccine across Europe.
The UK has bought enough vaccines from several manufacturers that the change in AstraZeneca policy should not significantly reduce the vaccination rate. But other countries are starving for doses. Cameroon and the Democratic Republic of Congo have already delayed injections of AstraZeneca’s vaccine increasingly in Europe. Any further hesitation, researchers said, could cost lives.
“In developing countries, the dynamic is either using the vaccine you have or you have nothing,” said Penny Ward, a visiting professor of pharmaceutical medicine at King’s College London. “In that case, carnage follows.”
For the vast majority of the population, British and European regulators said on Wednesday, the benefits of AstraZeneca’s shots far outweigh the risks. The coagulation problems occurred at a rate of approx. one in 100,000 recipients across Europe. Meanwhile, the vaccine in the UK has run down hospitalizations from Covid-19 – which in itself can cause serious coagulation problems – and saved thousands of lives, regulators said.
British health officials estimated that the risk of being admitted to an intensive care unit for Covid-19 outweighed the dangers of unusual blood clots in almost all age groups and at almost all levels of outbreaks.
However, because younger people are less likely to develop severe Covid-19, regulators said any vaccine given in that age group should clear a higher safety line. British data also suggest that younger people are more prone to the rare blood clots, making health officials there and in Europe more belligerent about giving them the vaccine.
In response to the new regulatory guidance, Italy on Wednesday recommended not giving the AstraZeneca shot to people under 60 years of age. A number of countries, including Germany, France, Canada and the Netherlands, had already stopped using it for younger people and set the age limit. 55 or 60. Norway and Denmark have put the shot in total while they investigate.
“The balance between benefits and risks is very favorable for the elderly, but it is more balanced for the younger people,” said Dr. June Raine, UK’s chief drug regulator.
The blood clots have drawn increased concern due to their unusual composition of factors: blockages in larger veins, often those that drain blood from the brain combined with low platelet counts.
The emergence of the cases in early March presented countries among among their most serious legislative tests since shots were administered. When vaccinating millions of people, problems would inevitably arise that were too rare to appear in clinical trials with thousands.
But while researchers called for a coordinated effort, health officials across Europe defied the European Medicines Agency’s recommendations and suspended injections of the AstraZeneca vaccine. Most resumed firing a few days later.
Some experts said the breaks were understandable, but the flip-flopping was disorienting, all the more so amid an ugly altercation between European lawmakers and AstraZeneca over drastic reductions in supply that led some political leaders to mistakenly maliciously vaccinate. Studies began to show that most people doubted the safety of vaccines in Germany, France and Spain.
Everywhere the use of the shot has suffered: Across Europe, 64 percent of the delivered doses of AstraZeneca’s vaccine have been injected into people’s arms, significantly lower than the rates of other shots.
“It was hoped that there would have been cooperation and more discussion between regulators instead of many different countries going in all possible directions,” Professor Ward said. “This aspect has really been the most ineffective.”
As doctors across Europe have studied the rare blood clots, they have become more convinced of a connection, no matter how poorly understood, with the vaccine.
The inoculation appeared to trigger an immune response targeting platelets in a small number of people, doctors and regulators said. The platelets in turn caused dangerous blood clots in various parts of the body, including in the brain, which in some cases led to a rare type of stroke.
But why some people generated platelet-targeted antibodies is not known, doctors have said. Some component of the vaccine or an excessive immune response in some recipients – or both – may be the cause. Existing conditions that make patients more vulnerable are not known.
More women than men have suffered these coagulation problems, but UK regulators said it appeared to be a result of women being vaccinated in higher numbers due to frontline medical roles.
Regulators have asked vaccine recipients and doctors to keep an eye out for certain symptoms, including severe and persistent headaches and small blood spots under the skin. Medical groups have circulated guidance on how to treat the disorder.
By March 22, regulators had conducted a detailed review of 86 cases, 18 of which were fatal, they said.
Concerns about the shot became acute enough in the UK this week that the University of Oxford, which developed the vaccine with AstraZeneca, stopped giving doses as part of a two-month-old trial in children.
“Safety has been our priority during the development of the vaccine,” said Andrew Pollard, the Oxford researcher in charge of the experiments on Wednesday. The identification of the blood clots, he added, “shows that the security system is working.”
In the United States, AstraZeneca is preparing to apply for an emergency use permit from the Food and Drug Administration. If and when they take up the application, the regulators of the Agency are expected to investigate the coagulation cases.
The US, flushed with vaccines from three other manufacturers, may not ultimately need AstraZeneca’s shots. But any FDA decision is expected to carry significant weight in some of the poor nations that rely on the shot.
The World Health Organization said a subcommittee on vaccine safety had met on Wednesday, noting that “rare side effects after immunizations should be assessed against the risk of death from Covid-19 disease and the vaccines’ potential to prevent infections.” It said that a connection with the coagulation problems, while “plausible”, had not been confirmed.
For the UK, the AstraZeneca vaccine has become a huge source of national pride and the backbone of the country’s rapid vaccination program.
Although younger people are at lower risk for severe Covid-19, researchers have said that inoculation remains crucial to provide adequate protection in the population to end the pandemic.
Emma Bubola, Monika Pronczuk and Rebecca Robbins contributed with reporting.