The Food and Drug Administration announced Wednesday that it has approved the first new influenza drug with a novel mechanism of action in nearly 20 years. The drug, Xofluza, is being brought to the U.S. market by Genentech, a division of Roche.

The approval comes just in time for flu season, which should begin in earnest in coming weeks.

The drug is a fast-acting treatment, taken in a single dose. A dose may be one or two pills, depending on the body weight of the person taking the drug. Someone sick with influenza must take it, though, soon after onset of symptoms to receive maximum benefit of the treatment.

The drug has already been licensed in Japan, where it is sold by Shionogi & Co. Roche bought most of the global rights to the drugs, though Shionogi retains the rights in Japan and Taiwan.

“With thousands of people getting the flu every year, and many people becoming seriously ill, having safe and effective treatment alternatives is critical.” FDA Commissioner Scott Gottlieb said in the agency’s statement announcing the approval. “This novel drug provides an important, additional treatment option.”

Genentech said the wholesale price of the drug will be $150, regardless of whether a prescription requires one or two pills. That’s on par, the company said, with other available flu drugs, including the best known, Tamiflu.

A spokesperson for Genentech said via email that the company will offer a coupon to eligible patients during the upcoming flu season, which would mean that people whose health insurance covers the drug and who use the coupon could pay as little as $30 for Xofluza in its first year on the market. The coupon will knock $60 off the price of the drug for people who do not have insurance, the spokesperson said.

Experts have predicted pricing will likely play a role in how much market acceptance there is for Xofluza. Tamiflu—which a study has suggested works as well as Xofluza—has not proved to be hugely popular. With Xofluza, though, the convenience factor of a one-and-done dosing regimen may make a difference. Tamiflu must be taken twice a day for five days.

The FDA approval process was rapid. The agency announced in late June that it would review the drug on a priority basis and expected to render a decision by Christmas. The company said then that if the drug was approved, it would work to get Xofluza into the distribution pipeline for this flu season.

Xofluza was approved for use in people 12 and older who have been experiencing flu symptoms for no more than 48 hours.

It is the first drug in a new class called endonuclease inhibitors. They work by interrupting viral replication—the process by which invading viruses take over the inner workings of cells to make hordes of copies of themselves to further spread the infection.

The drug acts quickly, but must be taken quickly as well for maximum effect. The studies used to support its licensure application found that people who took the drug within 24 hours of the start of symptoms felt better, on average, 33 hours sooner than people whose flu was untreated. But for those who started the drug later, their recovery was sped up by only about 13 hours.

That, experts have acknowledged, means there could be real-world hurdles to use of the drug. Patients will have to obtain prescription and get it filled within hours of starting to feel sick to gain the benefits.

The FDA noted that the most common adverse reactions in patients taking Xofluza included diarrhea and bronchitis.

Republished with permission from STAT. This article originally appeared on October 24, 2018