At least three companies are developing daily pills that can fight the coronavirus early after diagnosis and conceivably prevent symptoms from developing after exposure.

Timothy Sheahan, a virologist at the University of North Carolina-Chapel Hill who has helped pioneer these therapies said:

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.

The medications developed to treat and prevent viral infections in people and animals, work differently depending on the type. 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.

The top contender is a medication from Merck & Co. and Ridgeback Biotherapeutics called molnupiravir, Dieffenbach said. Two others include a candidate from Pfizer, known as PF-07321332, and AT-527, an antiviral produced by Roche and Atea Pharmaceuticals.

They work by interfering with the virus’s ability to replicate in human cells. In the case of molnupiravir, the enzyme that copies the viral genetic material is forced to make so many mistakes that the virus can’t reproduce. That, in turn, reduces the patient’s viral load, shortening infection time and preventing the kind of dangerous immune response that can cause serious illness or death.

So far, only one antiviral drug, remdesivir, has been approved to treat covid. But it is given intravenously to patients ill enough to be hospitalized, and is not intended for early, widespread use.

By contrast, the top contenders under study can be packaged as pills.

Sheahan, who also performed preclinical work on redeliver, led an early study in mice that showed that molnupiravir could prevent early disease caused by SARS-CoV-2, the virus that causes covid.

The formula was discovered at Emory University and later acquired by Ridgeback and Merck.

Clinical trials have followed, including an early trial of 202 participants last spring that showed that molnupiravir rapidly reduced the levels of infectious virus.

This daily orally administered medication, ideally a single pill, could be taken for five to 10 days at the first confirmation of covid infection.- CNN