Australia and the Philippines limited use of AstraZeneca's COVID-19 vaccine on Thursday, while the African Union dropped plans to buy the shot.
On Wednesday, the European Medicines Agency (EMA) said that it has found a possible link between AstraZeneca's COVID-19 vaccine and reports of very rare cases of blood clots in people who had received the shot. However, the possible causes are still unknown, a senior official for the European Medicines Agency (EMA) said in an interview.
The vaccine has been made by drugmaker AstraZeneca in collaboration with Oxford University. After reports linking it to a brain blood clotting disorder, more than a dozen countries have suspended the use of the vaccine due to growing safety concerns.
However, experts say that, even if a causal link between the vaccine and blood clots is proved, the risks to the general population of getting a serious clot are very less. Both the EMA and the World Health Organization have said the benefits outweigh the risks of the vaccine.
Meanwhile, Australia and the Philippines limited use of AstraZeneca's COVID-19 vaccine on Thursday, while the African Union dropped plans to buy the shot.
What are clots?
CVST stands for cerebral venous sinus thrombosis. Put simply, this is a clot found in a large vein in the brain.
Blood normally travels through veins from the brain back to the heart.
The CVST clot can block the flow of blood in the brain, reducing oxygen supply and potentially causing damage - stopping the central nervous system from working properly.
Rare clots have also been found in other areas, such as the large veins in the abdomen, in people who have had the Oxford-AstraZeneca jab, and, in a handful of cases, in some arteries (the vessels carrying blood from the heart to organs).
Time gap between vaccination and brain clot
Most cases have been seen between four days and a few weeks of people having the jab.
Medical experts in the UK now suggest doctors should consider this rare condition as a diagnosis in anyone who has matching symptoms up to a month after they have had the vaccine.
Data related to clot
According to the UK medical regulator, the MHRA, 79 cases have been identified, and 19 people have died.
This is out of a total of more than 20 million doses of the AstraZeneca vaccine which have been given in the UK.
The general risk of these types of clots following a jab is estimated to be one in 250,000.
Though still rare, this risk appears to increase in younger people.
Experts are clear that for the vast majority of people the benefits of the vaccine vastly outweigh the risks.
High points of AstraZeneca vaccine
Developed in collaboration with Oxford University, the vaccine has been a frontrunner in the global vaccine race
AstraZeneca's shot is sold for a few dollars a dose. It is by far the cheapest and most high-volume launched so far.
It has none of the extreme refrigeration requirements of some other COVID-19 vaccines, making it easier for the developing world.
Countrywise restriction
More than a dozen countries have at one time suspended or partially suspended use of the shot.
The Philippines suspended the use of AstraZeneca shots for people under age 60.
Australia recommended people under 50 should get Pfizer's COVID-19 vaccine in preference to AstraZeneca's.
The African Union dropped plans to buy the AstraZeneca shot amid global shortages.
Italy on Wednesday joined France, the Netherlands, Germany and others in recommending a minimum age for recipients of AstraZeneca's shot.
Britain said people under the age of 30-years should get an alternative.
South Korea also suspended use of the vaccine in people under 60 this week, while approving Johnson & Johnson's one-dose vaccine.
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