The European Medicines Agency (EMA) said it continues to investigate a number of thromboembolic events in people administered AstraZeneca’s COVID-19 vaccine AZD1222, whilst continuing to back the benefits of the immunization. The probe comes as a number of major EU nations, including France, Germany, Italy and Spain, joined other countries in pausing use of the vaccine.
According to the EMA, the decisions made by the individual countries are “a precaution taken in the light of their national situation,” adding that it “currently remains of the view that the benefits of the AstraZeneca vaccine in preventing COVID-19, with its associated risk of hospitalization and death, outweigh the risks of side effects.” The regulator indicated that its Pharmacovigilance Risk Assessment Committee (PRAC) will continue to review the data, with a meeting scheduled for March 18 to determine if any further actions are required.
“Highly unusual” symptoms behind decisions
Last week, safety concerns were raised over AZD1222, prompting Denmark, Iceland and Norway to pause use of the vaccine, with countries including Bulgaria, Ireland, the Democratic Republic of Congo, the Netherlands and Thailand later following suit. The Netherlands took the decision after its Pharmacovigilance Centre Lareb said that there were 10 cases of reported side effects in the country associated with the vaccine, including cases of possible thrombosis or embolisms.
Meanwhile, Germany’s health minister Jens Spahn said the move in his country was made on the advice of the Paul Ehrlich Institute, following “new reports of cases of cerebral vein thrombosis.” He added that seven such cases had been reported. Spahn remarked “in light of these newly reported cases, the Paul Ehrlich Institute today re-evaluated the situation and recommended a suspension of vaccinations and further analysis.” Last Friday, Spahn indicated there was no reason to discontinue using the vaccine in Germany, while Lothar Wieler, head of the Robert Koch Institute for Infectious Diseases, suggested that since the country was vaccinating many more older people now, “there can be a chronological link between vaccination and death,” but there is “no evidence that the link is statistically excessive.”
In announcing its decision last week, the Danish Health and Medicines Authority said one of the cases of blood clots was related to a death in Denmark. On Monday, the regulator explained that the person had “highly unusual” symptoms, including a low number of blood platelets and clots in small and large vessels, as well as bleeding. “It was an unusual course of illness around the death that made [us] react,” the Danish Health and Medicines Authority said, noting that a few similar cases were found in Norway and in the EMA’s database of drug side effects.
Blood-clot rate lower than in general population
In response to the safety concerns, AstraZeneca chief medical officer Ann Taylor noted that “around 17 million people in the EU and UK have now received our vaccine, and the number of cases of blood clots reported in this group is lower than the hundreds of cases that would be expected among the general population.” The EMA echoed this view, noting Monday that “many thousands of people develop blood clots annually in the EU for different reasons.”
According to AstraZeneca, a review of all available safety data of more than 17 million people vaccinated in the EU and UK with AZD1222 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. AstraZeneca indicated that so far across the EU and UK, there have been 15 events of DVT and 22 events of pulmonary embolism, which it said “is much lower than would be expected to occur naturally…and is similar across other licensed COVID-19 vaccines.”
As part of the recent emergency approval process for Johnson & Johnson’s COVID-19 vaccine Ad26.COV2.S, which like AZD1222 is also an adenovirus-vectored vaccine, US regulators highlighted some cases of thromboembolic events, including DVT and pulmonary embolism, that were numerically slightly more common among vaccine recipients than for placebo. The FDA said it considered these cases to be “of clinical interest,” but otherwise flagged no specific safety concerns linked to Johnson & Johnson’s product, which was authorized in the EU last week.