Molnupiravir: miracle pill?

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In the fight against the COVID-19 virus, a new drug has been introduced to significantly mitigate the disease’s effects. Named after Thor’s hammer, Mjölnir, the drug molnupiravir could be a powerful tool for reducing the risk of hospitalization and death among coronavirus patients. Here’s what you need to know about how the pill works, and what the advantages and disadvantages may be.

How it works

Developed by Merck and Ridgeback Biotherapeutics, molnupiravir is an easy-to-swallow pill that is meant for those infected with COVID who are not in the hospital. It is meant to be taken as soon as you begin to show symptoms for the virus—right as the virus starts to replicate rapidly and the immune system has not yet developed a defense.

Unlike bacteria, when viruses like COVID-19 enter the body, they are unable to reproduce without interfering with the machinery of host cells. Because of this, it is difficult to develop a drug that can damage a virus without also harming healthy human cells. 

As the SARS-CoV-2 virus spreads, it creates copies of itself with RNA instructions in order to continue reproducing. When the drug molnupiravir enters cells, it transforms itself into fake “RNA-like” building blocks. RNA polymerase (the machine that duplicates SARS-Cov-2) uses molnupiravir’s RNA-like materials in the virus’ genome. This fake genetic material is then connected to the viral genetic material. Afterward, when the virus attempts to replicate, the genetic code contains numerous errors.

“If you create enough errors or you create errors in parts of the virus that are absolutely critical, the virus can’t replicate,” said Daria Hazuda, vice president of infectious disease and vaccine research at Merck.

Molnupiravir works similarly to another antiviral drug for COVID known as remdesvir, as both treatments affect the replication of the virus while not damaging any human cells. However, remdesvir merely slows down the virus’ reproductive cycle rather than stopping it, making molnupiravir a much stronger tool to treat COVID. 

Molnupiravir could also be more effective than the only other treatment currently available for the early stage of COVID—monoclonal antibodies. Unlike molnupiravir, monoclonal antibodies are lower in supply, must be given by professionals, and can eventually become ineffective against viruses.

For more details on the inner workings of molnupiravir, check out this research paper.


Merck’s Phase 3 trial of molnupiravir has revealed that the drug has cut the risk of hospitalization or death in half. 7% of volunteers in the experimental group were hospitalized, and none died. Within the placebo group, 14 percent were hospitalized or died. Overall, the drug is expected to be more effective than other treatments simply due to the fact that it should be more accessible to the public. However, one downside is that it needs to be taken within a tight window—the first five or so days of illness. The pill can only work if people confirm they are COVID-positive with a test and receive a prescription in time.

Side effects

Because molnupiravir doesn’t cause any collateral damage to healthy human cells, no serious side effects have been reported yet by Merck. However, final data is still expected from the company upon publication. 


Molnupiravir is currently at a projected cost of $700 per course of treatment. The price is much cheaper compared to other treatments, which can cost between $2,000 and $3,000, but the drug still isn’t very affordable for many. Merck has pledged to develop a tiered pricing system that could reduce the cost of the pill abroad, and hopefully make the pills free in America, similar to the COVID vaccines.


Merck aims to receive emergency authorization for molnupiravir from the Food and Drug Administration (FDA) as soon as possible. After the drug is approved by regulators, it should hopefully be available by the end of this year. The company is aiming to produce enough pills for 10 million people in this timeframe. Unfortunately, this is nowhere close to enough for all Americans infected with COVID.

Because COVID vaccines have yet to gain a foothold in various other countries, molnupiravir could fill a gap in the global response to the virus. One issue, however, may be regarding testing; in order for countries to distribute the pill, access to quick COVID-19 testing is required, which could be difficult for some low-income countries. It’s key that wealthier countries don’t get more than their fair share of the pill. 

Overall, due to the drug’s high efficacy rates, lower cost, and convenient use, molnupiravir could certainly be a game-changer in the fight against COVID, especially if it is able to overcome issues with inventory and equity. Nevertheless, it is critical that vaccine distribution efforts continue alongside the distribution of molnupiravir, as experts insist that vaccines still offer the best protection.

“Vaccine equity is sort of the defining challenge of our time. But you never fight an infectious disease with just one set of tools,” says Rachel Cohen, the North American executive director at the Drugs for Neglected Diseases Initiative. “We really need the full arsenal of health technologies.”

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