Explained: Europe’s AstraZeneca pause

Which countries have temporarily suspended the use of the vaccine?

France, Germany, Italy, Netherlands Denmark, Norway, Iceland, Austria, Estonia, Bulgaria, Romania, Estonia, Lithuania, Luxembourg, and Latvia have temporarily paused the use of the vaccine. These countries have said the step is “a precautionary measure” and “pending further investigation” being carried out by the experts at the European Medicines Agency (EMA).

What is the EMA investigating?

On March 10, the EMA said Austria’s medicines regulatory authority has suspended use of a batch of the AstraZeneca vaccine (Batch ABV5300) after a person was diagnosed with multiple thrombosis (formation of clots within blood vessels) and died 10 days after vaccination. It said another person was hospitalised with a pulmonary embolism (a blockage in arteries in the lungs) after being vaccinated, and is now recovering.

As of March 9, reports of two other thromboembolic event cases had been received for this batch, the EMA said. Overall, 22 cases of thromboembolic events have been reported from among the 3 million people vaccinated with the AstraZeneca vaccine in the European Economic Area, it said.

Batch ABV5300 was delivered to 17 EU countries and comprises 1 million doses of the vaccine. “Although a quality defect is considered unlikely at this stage, the batch quality is being investigated,” the EMA has said.

What has been the progress of the EMA investigation?

On March 15, the EMA said events involving blood clots, some with unusual features such as a low count of platelets, have occurred “in a very small number of people” who received the vaccine. The EMA underlined that thousands of people develop blood clots annually in the EU “for different reasons”. “The number of thromboembolic events overall in vaccinated people seems not to be higher than that seen in the general population,” it said.

The EMA said it is working closely with experts in blood disorders and a “rigorous analysis of all the data related to thromboembolic events will be carried out in the coming days”. Its safety committee, PRAC, has called an extraordinary meeting on March 18 to discuss any further actions that may need to be taken.

The EMA has stressed that it currently remains of the view that “the benefits of the AstraZeneca vaccine in preventing Covid-19, with its associated risk of hospitalisation and death, outweigh the risks of side effects”.

What have regulatory authorities in European countries found so far?

AUSTRIA: On March 7, the Federal Office for Safety in Health Care (BASG) in Austria said it has received two reports in temporal connection with vaccination from the same batch (ABV5300) in the district of Zwettl: a 49-year-old woman who died as a result of severe coagulation disorders, and a 35-year-old woman who developed a pulmonary embolism and is on the way to recovery. It said that currently, there is no evidence of a causal relationship with vaccination. “Based on the known clinical data, a causal relationship cannot be established, as thrombotic events, in particular, are not among the known or typical side effects of the vaccine in question,” it said.

DENMARK: On March 11, the Danish Medicines Agency said it has received one report about death on the basis of blood clots, and that case is being assessed. “We do not know yet if the blood clots and the death reported in Denmark are related to the vaccine, but it should be thoroughly investigated as a precautionary measure,” said Tanja Erichsen, Head of Division, Danish Medicines Agency. The agency has recommended that people who have been vaccinated with the AstraZeneca vaccine in the last 14 days and who experience long-term symptoms — lasting for more than three days — should talk to their doctor. “Likewise, you should consult your doctor if you experience new symptoms within 14 days, after any common well-known transient symptoms occurring in the first days after vaccination have disappeared,” it has said.

What has AstraZeneca said?

On March 14, AstraZeneca said a “careful review” of all available safety data of more than 17 million people vaccinated in the EU and UK with its vaccine has shown “no evidence of an increased risk of pulmonary embolism, deep vein thrombosis (DVT) or thrombocytopenia” in any defined “age group, gender, batch or in any particular country”.

As of March 8, in the EU and UK, there have been 15 events of DVT and 22 of pulmonary embolism reported among those given the vaccine. “This is much lower than would be expected to occur naturally in a general population of this size and is similar across other licensed Covid-19 vaccines,” AstraZeneca said.

It has said that in clinical trials, although the number of thrombotic events was small, these were “lower in the vaccinated group”.

On quality, it said there are also “no confirmed issues related to any batch of our vaccine used across Europe, or the rest of the world”. “Additional testing has, and is, being conducted by ourselves and independently by European health authorities and none of these re-tests have shown cause for concern. During the production of the vaccine more than 60 quality tests are conducted by AstraZeneca, its partners and by more than 20 independent testing laboratories,” it said.

What is India’s position on these adverse reactions?

One of the two vaccines in India’s ongoing programme, Covishield from Serum Institute of India, is a version of the AstraZeneca-Oxford vaccine.

Dr N K Arora, an adviser to the National Adverse Events Following Immunization (AEFI) Committee and a member of WHO’s expert body on vaccine safety, said current evidence shows vaccine benefits outweigh the risks. “These countries have stopped temporarily. WHO has told them that the events are not related to the vaccine. Prima facie there is no association. These clots can present in any organ. Therefore it has be to seen in the context of the background and not in isolation,” Arora said.

Arora said the committee is looking at four specific issues related to adverse reactions. “Causality assessment is being done irrespective of the vaccine. There are four things: the causes of death and hospitalisation; whether they have any events suggestive of the clot; association with the background, which means if the events are higher than the expected rate then it is a matter of concern; and we are looking at if these events are related to a particular vaccine,” Arora said.

About serious AEFI in India, Arora said that in 38 out of 71 postmortem reports received so far, a causal link to the vaccine has been not been established. “Currently, whatever we are investigating, there is no causal linkage. All the events we have found so far are coincidental,” Arora said.