Vial of AstraZeneca vaccine against coronavirus (COVID-19) on the first day of a mass vaccination by police and fire departments at the Wanda Metropolitan Stadium.

Marcos del Mazo | LightRocket | Getty Images

The World Health Organization announced on Wednesday that coronavirus vaccination rollout should continue with the AstraZeneca-Oxford University shot while a security clearance is in progress.

The latest guidance from the global health authority comes after a number of European countries announced they would stop using the shot over concerns that it could be linked to reported cases of blood clots in the region.

The WHO Advisory Committee on Vaccine Safety has reviewed the available data on the vaccine. On Wednesday, the WHO issued a statement saying that “vaccination against COVID-19 will not reduce disease or death from other causes”.

“It is known that thromboembolic events are common. Venous thromboembolism is the third most common cardiovascular disease worldwide,” it said.

While it is routine for countries to signal potential post-immunization adverse events, particularly during mass vaccination campaigns, “this does not necessarily mean that the events are related to the vaccination itself.”

Still, it added: “It is good practice to investigate them. It also shows that the surveillance system is working and that there are effective controls in place.”

WHO is in regular contact with the European Medicines Agency (EMA) and regulators around the world for the latest information on the safety of Covid-19 vaccines.

WHO said it would immediately share the results with the public once its review is complete. “Currently, WHO believes that the benefits of the AstraZeneca vaccine outweigh the risks and recommends that vaccinations be continued,” she added.

“An ongoing process”

Sweden, Lithuania and Latvia were the last countries on Tuesday to suspend use of the Oxford AstraZeneca vaccine for blood clot problems, following in the footsteps of Germany, France, Spain, Italy and Ireland, among others. More than a dozen European countries have temporarily stopped using the vaccine.

EMA executive director Emer Cooke said at a news conference Tuesday that a safety review of the shot was “an ongoing process,” but said that in a mass vaccination program of millions of people, some reports of adverse events were not unexpected to obtain .

Experts brought together by the EMA are tasked with deciding whether there is a causal link between the handful of adverse events with blood clots and the vaccine.

“This requires a very thorough analysis of all the data,” said Cooke. “Currently there is no evidence that vaccination caused these events,” she repeated, adding that the key health benefits of the vaccination program and the AstraZeneca shot it contained continued to outweigh the risks.

“Thousands of people die every day in the EU … these are very rare thromboembolic events or blood clots.” The EMA is expected to complete the review on Thursday.

Astounded health professionals

The strategy of these EU states has baffled health experts and raised concerns that the move could further damage confidence in the vaccine and slow down an already sluggish vaccination program on the block, while many countries have seen an increase in infections due to infectious coronavirus variants .

Some analysts have questioned whether the decision, given previous doubts about AstraZeneca’s study data, its effectiveness in people over 65 (various studies have shown it to be highly effective in reducing Covid-19 cases, hospitalizations and deaths ) and disputes has a political dimension over vaccine stocks.

Not all European countries have stopped using the shot. Belgium, Poland and the Czech Republic have all announced they will continue to use the shot, stating that the benefits outweigh the risks. Belgium went further and its health minister said interrupting the vaccination program was “irresponsible”.

AstraZeneca has vigorously defended its vaccine, stating in a statement Sunday that the number of blood clots recorded after vaccination was fewer than would naturally be expected.