After the vaccines, pharmaceutical companies are lining up to develop a treatment that can be simply taken at home with a glass of water when symptoms appear.
While prevention is better than cure, as the saying goes, knowing how to cure still remains crucial.
It will be several years before vaccines are widely available. And even when they are widely available, some people will still refuse the shot. Eventually, a very small number of people who are vaccinated will continue to get sick.
What is an antiviral?
Antivirals already exist for other viruses, such as HIV, which causes AIDS, or influenza (Tamiflu prescriptions).
At the beginning of the pandemic, funding and research focused on vaccine development, which partly explains the delay in developing antivirals for the coronavirus.
How do they work?
Viruses are little machines that need certain components to replicate. Antivirals are usually small chemical molecules designed to interfere with this machinery. They introduce mutations into the virus, and when this happens multiple times, these mutations reduce the virus’s ability to replicate.
By slowing down the disease, severe cases, hospitalizations and deaths can be avoided.
Two projects are currently relatively in advanced stages and are being tested in more than a thousand people (“phase 3” clinical trials).
The first is that of the pharmaceutical laboratory Merck, in partnership with the biotechnology company Ridgeback Biotherapeutics. The product is called molnupiravir. Originally developed to treat the flu, it has been modified so that it can be taken in pill form. The pill should be taken twice a day for five days.
The treatment has been very well tolerated by the few hundred people who have already received it. Analysis of several dozen of them showed that the virus was undetectable after five days in all the people treated with molnupiravir, but was still detectable in 26 percent of the placebo group. Results of the studies in 1,450 more adults are expected in the fall.
The second project is a collaboration between the Swiss pharmaceutical company Roche and the US company Atea Pharmaceuticals. The treatment, called AT-527, will be tested in about 1,400 participants in Europe and Japan, this time starting at age 12.
“We hope to submit for regulatory approval by the end of the year and launch the drug in 2022,” Jean-Pierre Sommadossi, CEO of Atea, told AFP.
A third, less advanced project is being developed by Pfizer. Unlike the others, the drug, called PF-07321332, was not repurposed but specifically designed to target SARS-CoV-2, the virus that causes Covid-19. It is being tested on about 60 adults, with results expected by the end of June.
Drugs must be taken early
Both Merck and Roche require that the drugs be taken within five days of the onset of symptoms. This is because the virus replicates most in the first week. The earlier you treat with an antiviral, the better the outcome.
This explains the relative failure of remdesivir, the only antiviral approved so far against covid-19, which is made by Gilead Sciences and must be administered intravenously in the hospital. Thus, patients are usually too far advanced in the disease to get any real benefit from it.
Once the pills are available, the biggest challenge will be to diagnose patients early. As a result, home testing kits will become increasingly important.
Benefits: Prevention and variants.
However, these antivirals should also be able to be used for prevention: For example, if one member of a family gets infected, the others can take the treatment to prevent them from getting sick. Scientists know that this use of Tamiflu is very effective against influenza.
Finally, experts are confident that antivirals will continue to be effective against the current variants and any other coronaviruses that may appear in the future.
This is a significant advantage over another existing treatment, synthetic antibodies. Not only are the antibodies limited because they are injected intravenously, but they are also highly specific to the virus they are targeting, so they are unlikely to be effective against future coronaviruses.