AstraZeneca's (AZN) COVID-19 vaccine has been cleared of causing blood clots that spurred several pauses in vaccine administration in Europe, Africa, and Asia this past week.

The final green light came from the European Union's Medicines Agency after an emergency meeting Thursday.

"Our scientific position is that this vaccine is a safe and effective option," said EMA executive director Emer Cooke, adding that the vaccine was not associated with an increased risk of blood clots.

But the agency will continue to monitor side effects and adverse events, EMA officials said, noting that there were rare occurrences of blood clots in clinical trial data, autopsies and clinical data, especially among young women.

As a result, the agency is looking into which sub-groups could be more at risk and "cannot rule out definitively a link" between the vaccine and clots, Cooke said.

In a statement Thursday, AstraZeneca said it would continue to work with regulators and health authorities, including updating product information and patient leaflets.

The European Medicines Agency, the U.K. regulatory agency (MHRA) and World Health Organization (WHO) have all said the benefits of the vaccine outweigh its risks.

"Our review has found that the available evidence does not suggest that blood clots are caused by COVID-19 Vaccine AstraZeneca," said Sir Munir Pirmohamed, chair of the U.K.'s commission on human medicines, in a statement Thursday.

The WHO released a statement Wednesday, which was echoed by the European head of the WHO Thursday, confirming the vaccine was safe to use.

"Vaccination against COVID-19 will not reduce illness or deaths from other causes. (Blood clots are) the third most common cardiovascular disease globally ... it is routine for countries to signal potential adverse events following immunization. This does not necessarily mean that the events are linked to vaccination itself," the statement said.

But the hurdles for AstraZeneca do not end there. The company is facing political tensions in Europe and India that are threatening the supply of the vaccine. The U.K. has had the best vaccination rate among European countries, but the vaccine has been largely produced in Europe and India.

The European Union is threatening an export ban to boost its vaccinations, while India's Serum Institute is being pressured by the Indian government to direct more doses internally. India is seeing some of the highest daily case rates, with some states implementing strict lockdowns and curfews again.

AstraZeneca, through the WHO, and Pfizer (PFE)/BioNTech (BNTX), through government contracts, have the largest share of global vaccinations to-date, according to the New York Times. But Pfizer's contracts are largely with North American and European countries.

Amid the political tensions surround the AstraZeneca vaccine, Russian and Chinese vaccines are seeing increased demand in South American and African countries.

The WHO has criticized the moves by wealthier countries, saying that while healthy individuals are being vaccinated, frontline workers in countries that are poorer or don't have manufacturing capacity are being left exposed to the virus.

Scientists and researchers have called for the U.S. to begin donating doses, as it and other wealthy countries are over-contracted for doses available for the population. U.S. officials have said they will consider donations after the population is fully vaccinated, even as health officials have said the country is ensuring there are enough vaccine doses being produced for potential boosters later in the year.

The U.S. is also sitting on a stash of AstraZeneca doses, even though the vaccine is not authorized by the U.S. Food and Drug Administration.

A White House official told Yahoo Finance on background the U.S. had been looking at the feasibility of loaning doses to Mexico and Canada.

"Our top priority remains vaccinating the US population, but the reality is that this virus knows no borders and ensuring our neighbors can contain the virus is mission-critical to protecting the health and economic security of Americans and for stopping the spread of COVID-19 around the globe," the official said.

Press Sec. Jen Psaki said Thursday the U.S. has 7 million releasable doses, of which 1.5 million doses could be sent to Canada and 2.5 million to Mexico. She said the numbers weren't finalized, and its possible additional countries could receive doses.

Meanwhile, the U.S. is on its way to meeting the goal of 100 million vaccinations in 100 days of the new administration, with nearly 74 million adults receiving first doses, according to the U.S. Centers for Disease Control and Prevention (CDC).

More from Anjalee:

• Novavax CEO: If FDA waits for US data, 'the lag will be a couple of months' for its vaccine

• China, Russia playing 'greater-than-expected' roles in global pandemic response

• Biden COVID-19 adviser: Vaccine news is great, but we still have a ways to go

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