ZURICH (Reuters) – Europe’s drug regulator said on Wednesday he had found a possible link between AstraZeneca’s COVID-19 vaccine and very rare blood clots in adults who received the shot. Britain has recommended that people under 30 get an alternative COVID-19 vaccine if possible.
This is what we know so far:
WHAT HAPPENED?
The EMA said the vaccine side effect monitoring system received 169 reports from April 4, 169 of cases of cerebral venous sinus thrombosis (CVST), or blood clots in blood vessels leaving the brain and 53 cases of splanchnic arterial thrombosis (SVT), or clotting in veins in the abdomen.
This is from approximately 34 million doses of AstraZeneca vaccine administered in Britain and the European Economic Area since vaccinations began almost three months ago.
The safety committee reviewed 62 cases of CVST and 24 cases of SVT, 18 of which were fatal.
Most reported cases occur in women under 60, but can be misleading. Germany and Britain say many more women got AstraZeneca’s lap than men.
Most cases occurred within two weeks of receiving the first dose.
German vaccination officials who recorded 29 cases of CVST in women aged 20 to 59 years who received the AstraZeneca vaccine said the incidence in that group was 20 times higher within 16 days after vaccination than would normally be expected.
The German Ministry of Health said that 1 to 1.4 cases of CVST would be expected during the time.
WHAT DID THE REGULATOR OF BRITAIN SAY?
The Regulatory Agency of Medicines and Healthcare Products reviewed 79 cases of rare clotting along with low platelets, with 19 deaths, 13 women and 6 men. Eleven of the deaths in people under 50 and three under 30.
All 79 cases occurred after a first dose of the vaccine.
HOW DID REGULATORS DECIDE?
British officials used statistics from the Winton Center for Risk and Evidence Communication of the University of Cambridge to explain their recommendations that young people get an alternative chance, while older people still get AstraZeneca.
According to the center, vaccination with the AstraZeneca shot will reduce admissions to intensive care units by nearly seven out of 100,000 people in the 20- to 29-year-old group at high risk for exposure to the virus, while 1.1 people per An estimated 100,000 people in the same group could suffer serious vaccine-related damage.
The risk of serious harm from vaccination decreases further as older people get vaccinated, and admissions to vaccine-prevented ICUs rise sharply, increasing the benefit-to-risk ratio of the AstraZeneca shot. The center concluded that only 0.4 people for every 100,000 in the 50-59 age group would be vaccinated, while 95.6 ICU admissions per 100,000 people would be prevented.
EMA researchers examined whether the frequency of events in the vaccinated population was higher than the normal background figures drawn from public health statistics or insurance records. This would be combined with a medical analysis of each case and insight from scientific literature.
In its findings, on March 18, the EMA said that on average, only 1.35 cases of CVST could normally be expected within 14 days of receiving AstraZeneca’s vaccine among people under 50, while 12 cases were recorded on the same cut-off date. .
By comparison, four women out of 10,000 would get a blood clot due to oral contraception.
The key to the EMA’s evaluation that benefits outweigh the risks is its conclusions about the likelihood of an increased risk of coagulation, compared to the benefits of COVID-19 and the reduction of hospitalizations and deaths.
WHAT IS THE EU DOING NOW?
The EMA said that low-platelet abnormal blood clots should be listed as a very rare side effect, and that countries should decide how to proceed with their national COVID-19 vaccination campaigns.
This can vary from country to country, the EMA said, depending on factors such as how quickly infections spread and whether vaccines are available. The safety committee has requested new studies and changes to the ongoing studies to provide more information on the mechanism behind the rare blood clots.
AstraZeneca and European regulators said concerns during blood tests did not emerge.
ARE THERE ANY THEORIES WHY CAN THE BATTLES LEAD?
One of the possible causes for the investigation of these rare cerebral sinus clots is that the vaccine rarely causes an unusual antibody.
The EMA said the vaccine could trigger an immune response that leads to the unusual clotting, although it acknowledges that scientists have yet to identify any risk factors that could cause someone to clot in combination with low platelets.
German scientists at Greifswald University have concluded that the vaccine has been linked to side effects, although their work still requires peer review. Andreas Greinacher, an expert on drug-induced immune responses, said that samples he examined showed unusual antibodies that activate platelets, causing the blood clots.
Greinacher is still looking for clues as to why some people had blood clots and others did not.
Reporting by Ludwig Burger in Frankfurt, Matthias Blamont in Paris and John Miller in Zurich; Additional reporting by Kate Kelland and Alistair Smout in London and Julie Steenhuysen in Chicago; Edited by Josephine Mason and Angus MacSwan