The United States may not need AstraZeneca’s COVID-19 vaccine, even if it wins U.S. regulatory approval, Anthony Fauci, the nation’s top infectious disease doctor told Reuters on Thursday, April 1.

The vaccine, once hailed as another milestone in the fight against the COVID-19 pandemic, has been dogged by questions since late last year, even as it has been authorized for use by dozens of countries, not including United States.

Fauci, director of the National Institute of Allergy and Infectious Diseases and chief medical adviser to the White House, said the United States has enough contracts with other vaccine makers to vaccinate its entire population, and possibly enough for booster shots in the fall.

Asked whether the United States will use the AstraZeneca vaccine doses, he said, “That’s still up in the air. My general feeling is that given the contractual relationships that we have with a number of companies, that we have enough vaccine to fulfill all of our needs without invoking AstraZeneca.”

Concerns on blood clotting

Late last year, the drugmaker and Oxford University published data from an earlier trial with two different efficacy readings as a result of a dosing error. Then in March, more than a dozen countries temporarily suspended the use of AstraZeneca’s vaccine after reports linked it to a rare blood clotting disorder.

British regulators on Thursday said they have identified 30 cases of rare blood clot events after the use of the AstraZeneca COVID-19 vaccine, 25 more than the agency previously reported.

The Medicines and Healthcare products Regulatory Agency said it had received no such reports of clotting events following use of the vaccine made by BioNTech SE and Pfizer Inc.

The health officials said they still believe the benefits of the vaccine in the prevention of COVID-19 far outweigh any possible risk of blood clots.

Some countries are restricting use of the AstraZeneca vaccine while others have resumed inoculations, as investigations into reports of rare, and sometimes severe, blood clots continue. (READ: ‘Benefits outweigh risks’: PH to continue AstraZeneca jabs amid concerns in Europe)

On March 18, the UK medicines regulator said that there had been five cases of a rare brain blood clot among 11 million administered shots.

On Thursday, it put the count at 22 reports of cerebral venous sinus thrombosis, an extremely rare brain clotting ailment, and 8 reports of other clotting events associated with low blood platelets out of a total of 18.1 million doses given.

Also in March, a U.S. health agency said data from the company gave an incomplete picture of its efficacy. Days later AstraZeneca published results showing diminished, though still strong, efficacy.

Fauci said that “If you look at the numbers [of doses] that we’re going to be getting, the amount that you can get from J&J, from Novavax, from Moderna if we contract for more, it is likely that we can handle any boost that we need, but I can’t say definitely for sure.” – Rappler.com