Who's going to raise these kids?"

But the Kellys, who live in Seattle, had agreed just after their diagnoses to join a clinical trial at the nearby Fred Hutch cancer research center that's part of an international effort to test an antiviral treatment that could halt covid early in its course.

By the next day, the couple were taking four pills, twice a day.

"To have all these underlying conditions, I felt like the recovery was very quick."

The Kellys have a role in developing what could be the world's next chance to thwart covid: a short-term regimen of daily pills that can fight the virus early after diagnosis and conceivably prevent symptoms from developing after exposure.

"Oral antivirals have the potential to not only curtail the duration of one's covid-19 syndrome, but also have the potential to limit transmission to people in your household if you are sick," said Timothy Sheahan, a virologist at the University of North Carolina-Chapel Hill who has helped pioneer these therapies.

Antivirals are already essential treatments for other viral infections, including hepatitis C and HIV.

But they can be engineered to boost the immune system to fight infection, block receptors so viruses can't enter healthy cells, or lower the amount of active virus in the body.

At least three promising antivirals for covid are being tested in clinical trials, with results expected as soon as late fall or winter, said Carl Dieffenbach, director of the Division of AIDS at the National Institute of Allergy and Infectious Diseases, who is overseeing antiviral development.

"I think that we will have answers as to what these pills are capable of within the next several months," Dieffenbach said.

The top contender is a medication from Merck & Co.

The same month, the administration said it would invest $3.2 billion in the Antiviral Program for Pandemics, which aims to develop antivirals for the covid crisis and beyond, Dieffenbach said.

The pandemic kick-started a long-neglected effort to develop potent antiviral treatments for coronaviruses, said Sheahan.

Though the original SARS virus in 2003 gave scientists a scare — followed by Middle East respiratory syndrome, or MERS, in 2012 — research efforts slowed when those outbreaks did not persist.

"The commercial drive to develop any products just went down the tubes," said Sheahan.

Widely available antiviral drugs would join the monoclonal antibody therapies already used to treat and prevent serious illness and hospitalizations caused by covid.

It's still too early to know how the price of antivirals might compare.

Like the monoclonal antibodies, antiviral pills would be no substitute for vaccination, said Griffin.

Studies evaluating whether antivirals can prevent infection after exposure.

"Think about that," said Duke, who is also overseeing a prophylactic trial.