What we know about Merck's experimental pill to treat COVID-19

The first experimental pill to fight the virus that causes COVID-19 is on the way, according to pharmaceutical giant Merck & Co. But Canadian experts caution that vaccination is still the best way to prevent severe outcomes from the disease.

At this point, Merck has only put out a news release about molnupiravir, not the full results of the drug's trial, so infectious disease experts still have many questions.

Nonetheless, Dr. Lynora Saxinger, an infectious diseases specialist at the University of Alberta in Edmonton, said the drug does offer hope.

If it proves as effective as Merck says, it could reduce hospitalizations and deaths from COVID-19 and help ease strain on health-care systems, she said.

"It definitely would make a difference," she told Dr. Brian Goldman, host of White Coat, Black Art and The Dose. "[But] you're never going to get the incremental benefit that you get from vaccination. So I think this is relevant to places where there's low vaccination for whatever reasons."

Here is what we know about molnupiravir.

What is the drug? 

Similar to antiviral drugs for other illnesses such as HIV, molnupiravir attaches to the virus and introduces errors so it can no longer make active copies of itself. 

"It basically is like a Trojan horse to the virus to make it mix up its own code," said Saxinger. 

According to Merck, no deaths were reported among patients in the trial who received molnupiravir. The company says the trial results suggest the drug reduced the overall risk of hospitalization or death from COVID-19 by approximately 50 per cent compared to patients who received the placebo.

The trial was stopped early due to those positive results, but they have not yet been peer reviewed by experts who aren't connected to the research.

Saxinger has questions about how the drug's effectiveness was measured. 

The trial apparently looked at hospitalization rates, she said, but it was a multinational trial and the threshold at which different countries admit patients to hospital might differ. 

Specific data about a patient's oxygen levels and the amount of supplemental oxygen needed would be more objective indicators of the drug's effectiveness, she said.

Who could benefit from this drug? 

If approved, molnupiravir would be the first pill available to treat COVID-19, making it easier to administer than the currently available intravenous drugs.

Saxinger said one of the challenges would be to determine which types of patients are most likely to benefit from the drug and figure out how to deliver it to those people preferentially.

"That's where you get the biggest bang for your buck in reducing the severe outcomes," she said.

The 775 patients in the trial had mild-to-moderate symptoms, and had at least one risk factor associated with poor outcomes from COVID-19. 

Dr. Srinivas Murthy, an infectious diseases and critical care physician with the University of British Columbia's faculty of medicine, said the study appears to have involved only unvaccinated patients, which raises questions.

"Do we think that this drug will be similarly effective in those who are vaccinated and is it worth it to try it in those populations?" he said.

The price of the drug is also a concern for Murthy. Merck has a contract with the U.S. government to manufacture 1.7 million courses of molnupiravir for $700 US per course.

Although it's not yet clear what the Canadian purchase price will be, Murthy said that's an important consideration.

"How accessible is it?" he said.

Equity should be at the core of decisions about the drug's distribution, he said. 

Timing limitations 

Provided the data ultimately backs up Merck's claims, both Murthy and Saxinger say molnupiravir could make a difference in the fight against COVID-19.

"The fact that there [would be] an oral, available, safe, effective anti-viral medication that could prevent hospitalizations would be, if true, outstanding," said Murthy. 

But like with other medications that have an antiviral effect, it appears timing could be key. The company said the drug shows promise when given to people within five days of the start of symptoms. Saxinger said that could present a challenge.  

"One of the things we're struggling with is that people are not having their infection identified until they're severely ill," she said. "You'd have to have a really efficient system to make sure people are getting diagnosed quickly and triaged for treatment quickly."

Merck has not yet released any details about potential side-effects.

When might it be available?

Merck has said it plans to apply for emergency use authorization to the U.S. Food and Drug Administration as soon as possible. Health Canada has been reviewing data for molnupiravir since August, but officials have said there's no timeline for completing the review.

Saxinger said the company will have to provide a data package to regulators.

Murthy said it will be at least a few weeks before more data on the study is available. He has "cautious optimism" about the drug's ability to help treat the illness, but said it won't serve as a replacement for COVID-19 prevention. 

"The vaccine [has] double or triple the effect of preventing hospitalization," he said. "And so, really, the message seems to be and continues to be: Get vaccinated."

Written by Rachel Sanders