U.S. drug regulators on Wednesday issued an emergency use authorization for the first oral antiviral coronavirus pill, developed by pharmaceutical giant Pfizer Inc.

The pill, called Paxlovid, is authorized for mild-to-moderate coronavirus cases in patients aged 12 or older facing high risk of severe illness, and can be taken at home. The company is ready to ship limited supplies of the treatment, whose complex production process requires six to eight months for each batch.

Antiviral pills against COVID-19 being developed by U.S. pharmaceutical company Pfizer Inc., shown in an undated photo. (Photo courtesy of Pfizer)(Kyodo)

"Everyone agrees this is a very promising antiviral, and therefore, we want to make sure that production is ramped up as quickly as possible," Jeff Zients, the White House COVID-19 response coordinator, told a press conference.

Calling the treatment a "breakthrough" therapy, Pfizer Chairman and CEO Albert Bourla said Paxlovid "will change the way we treat COVID-19, and hopefully help reduce some of the significant pressures facing our healthcare and hospital systems.

Paxlovid is designed to prevent viral replication. It is administered as a set of three pills, to be taken twice daily for a span of five days.

Treatment with the pills, which will be available by prescription only, should begin as soon as possible after a COVID-19 diagnosis and within five days after symptoms develop, according to the U.S. Food and Drug Administration. It noted that Paxlovid is not approved to prevent COVID-19 nor will it substitute for vaccination.

Pfizer said in a press release that it is ready to start immediate delivery in the United States, in accordance with its agreement with the U.S. government to supply 10 million treatment courses between 2021 and 2022.

It also raised its production projection for next year from 80 million to 120 million courses of treatment.

Earlier this month, Pfizer said the experimental pill had shown nearly 90 percent efficacy in preventing hospitalization or death in high-risk patients, citing final study results.

People with diabetes and heart disease are among those considered to be at high risk of getting seriously ill from COVID-19.

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