What New Antiviral Medications from Merck and Pfizer Could Mean for the Future of COVID-19 

As the SARS-CoV-2 virus that causes COVID-19 continues to mutate and potentially undermine the effectiveness of current vaccines, Merck and Pfizer’s antiviral medications provide hope. Research indicates that these medications are expected to work against all versions of the virus, which could potentially change the course of the pandemic, offering a treatment that could withstand mutations. 

Let’s examine how these two antiviral medications function and what this could mean for the future of this virus. 

What Are The New Covid Medications and How Do They Work?  

Molnupiravir and Paxlovid are two new oral antiviral drugs developed to help the body fight against SARS-CoV-2. Molnupiravir was originally invented at Drug Innovations at Emory (DRIVE), LLC, but the pharmaceutical company Merck has been developing the Molnupiravir medication in conjunction with Ridgeback Biotherapeutics. Pfizer, the same company that developed one of the three FDA-approved COVID-19 vaccines has developed the other current oral antiviral medication, Paxlovid. 

Both the Paxlovid and Molnupiravir are administered as a series of pills, taken twice daily over the course of five days. Paxlovid is taken with one dose of the additional pill Ritonavir, which is a medicine that helps keep other medicines active in the body for longer periods of time. 

To fully comprehend how Paxlovid and Molnupiravir function, we must first take a look at how the coronavirus functions. Once the virus enters a human cell, it generates a copy of itself, allowing it to quickly spread and move through the body on its way to infect others. Once the medication is taken, it begins inactivating certain components of the virus’s replication mechanisms, which in turn prevents it from growing and spreading. 

What is the Difference Between Paxlovid and Molnupiravir?

The main difference between the two medications is the phase of virus replication in which they attack. Molnupiravir causes the amino acids that make up proteins to be rearranged, resulting in faulty proteins — and a virus that is unable to infect new cells or replicate itself.  This drug is a nucleoside analogue with a mechanism of action that tries to build faults into the virus’s genome coding. The potential worry about this medication is that it theoretically can cause unexpected mutations in the body outside of the virus. 

Paxlovid, on the other hand, disrupts the virus’s second stage of reproduction, when it uses a type of enzyme called a protease to shred the protein string in precisely the right places, forming the virus’s building blocks. Proteases function as molecular scissors, cutting large molecules into smaller fragments that aid in the creation of new viruses. The medicine inhibits the enzyme, preventing the virus from progressing past this point. 

How Effective are these COVID Medications? 

Due to the nature in which these drugs fight the virus, research indicates that they will likely remain effective against future variants, even if protection from our current vaccines and treatment begin to wane.

The trial figures provided by the two companies suggest Pfizer has the more effective and safer medicine out of the two. Pfizer released their preliminary results showing that their drug reduced the risk of serious illness and death by nearly 90 percent.  Merck’s data analysis shows that when taken within five days of the onset of symptoms, the Molnupiravir pill can reduce the risk of serious sickness, hospitalization, and death by 30 percent. It’s important to note that these results may change upon further testing and real world experience across the globe.. 

What Does This All Mean for the Future of COVID-19?

According to the National Institutes of Health (NIH), there are only three current FDA authorized treatments for COVID-19 patients who have not been hospitalized. However, these are all monoclonal antibody treatments, which are administered using intravenous (IV) infusions or injections and require an outpatient visit. In contrast, these new medications are cheaper to make and even easier to distribute and take, which makes it a more accessible option overall, especially in places of the world that do not have good vaccine coverage. 

However, there are still concerns about potential side effects of this type of drug, which could mean that it would not be recommended for all age groups or demographics. For example with Molnupiravir,  there are currently concerns that the drug may trigger the development of new variants or that they may interfere with fetal development during pregnancy. 

Because the Pfizer drug attacks during a different stage in the reproductive process of the virus, these same concerns do not directly apply. The secondary  pill Ritonavir that pairs with Paxlovid has been known to cause mild side effects such as nausea and vomiting. 

Drugs such as Paxlovid and Molnupiravir could change the course of the pandemic if real-world applications match trial results. The SARS-CoV-2 virus has killed over 5.3 million people across the globe in large part due to its ability to mutate and spread. Continuing to discover and develop  similar medications that target other aspects of the virus would give us a higher chance of mitigating the risk of COVID-19 infection.

It’s important to note that these new treatments are not intended to be a substitute or replacement for vaccination. The pills were designed to be taken by someone who has fallen ill, as an additional support.