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COVID-19 Antiviral Pills: What Are They and How Do They Work?

Dr. Muhammad Asad Arshad

4 min read

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COVID-19 antiviral pills are here! They include Lagevrio (Molnupiravir) and Paxlovid developed by Merck and Pfizer respectively. Let’s take a look at what they are and how they work.

What Are Antiviral Pills?

Antiviral Pills are oral drugs that help you fight against viruses that cause infection. These pills aid your body in fighting against the infection caused by the virus by reducing the intensity of the virus. Antiviral pills also help patients in recovering from viral infections in relatively less time when compared to other drugs.

In majority of the cases, viruses do not cause chronic infection. However, if the virus takes a deadly turn in a case, antiviral drugs can be a life-saver. This is the reason these pills actively work in treating COVID-19.

What are COVID-19 Antiviral Pills?

According to a recent update, the most anticipated oral drugs to combat the COVID-19 have been developed. Two companies, namely Pfizer and Merck, have introduced these antiviral pills in the pharmaceutical industry to fight against the virus. Upon testing, these drugs have shown promising results in reducing the severity of symptoms. However, the companies are still waiting for FDA’s approval to use these drugs for the general public.

These drugs will not only lower the number of hospitalizations, but if approved they will be a huge milestone in the fight against COVID-19. Unlike previous antivirals available for COVID-19, these drugs are oral drugs. Hence, patients will be able to take these pills at home. Also, these pills will be comparatively cheaper, which will definitely make them a good alternative to expensive antivirals and masses will be able to access them easily.

Britain is the first country to approve the use of Merck’s antiviral pills for patients with mild to moderate symptoms after the company claimed to half the number of hospitalizations. Thus, if the company is able to defend its claim, it will be making a huge impact on the casualties from COVID-19.

Merck’s antiviral pill will be sold under the brand name Molnupiravir. Likewise, Pfizer’s pill will be available under the brand name Paxlovid.

Types of COVID-19 Antiviral Pills

Here is a brief intro of both pills:

1. Lagevrio (Molnupiravir)

Molnupiravir is developed by Merck and is yet to be approved by the FDA. However, it has shown promising results in decreasing the number of hospitalizations for people who are at risk of developing serious symptoms of COVID-19. Hence, Merck has applied for emergency use authorization and the decision by FDA is expected to be finalized by the end of November.

Merck conducted a study by calling in 775 participants. These participants were selected after considering these factors:

  1. Participants must have mild to moderate symptoms of COVID-19
  2. Participants must have at least one factor that puts them at high risk of hospitalization
  3. Participants must enroll themselves for study within the initial five days of experiencing these symptoms

The result of this study prominently showed that this antiviral pill lowered the number of hospitalizations by half. So the pill is now available for use in Britain to people who have at least one factor that makes them more susceptible to severe symptoms of COVID-19.

2. Paxlovid

Paxlovid is an antiviral pill developed by Pfizer and it has shown promising results against COVID-19. A recent study by Pfizer suggests that it reduces the risk of hospitalization by up to 89% if the treatment starts within the initial three days of symptoms.

On the other hand, if treatment starts within the initial five days, the drug was successful in reducing the risk of hospitalization to almost 85%. However, the company still needs to file for emergency use authorization approval by FDA.

How do COVID-19 Antiviral Pills work?

How Does Molnupiravir Work?

Molnupiravir works by altering the replication process of the COVID-19 virus. It is a polymerase inhibitor that lowers the spread of the virus by introducing error into the genetics of the virus until it is no longer capable of surviving.

As a result, patients do not experience severe symptoms as they may have otherwise. However for the pills to be 100% effective patients must take these pills in the initial five days of being symptomatic.

How Does Paxlovid Work?

Paxlovid combines two components, one is an experimental molecule PF-07321332, and another is the drug ritonavir. This pill is a protease inhibitor in which the experimental molecule PF-07321332 combats the virus by interfering with its replication. It does so by blocking the enzyme that is responsible for replication.

While the other component ritonavir makes sure that PF-07321332 stays in the body long enough to fight by slowing down the breakdown of the molecule. Hence, ritonavir stops other enzymes from destroying the main component working on the COVID-19 virus. However, it is important to under that this oral drug is entirely different from the Pfizer-BioNTech vaccine.

Is There Anything Similar in Both Pills?

The formulas of both may be different but the main goal of both pills is to stop the replication of the virus in the patient’s body. They work in a similar manner by interfering with the replication of the COVID-19 virus. As a result, they help in reducing the intensity of symptoms.

However, for these pills to be effective, patients must start taking them within the initial five days of developing the symptoms. Another similarity among both pills is that they are oral drugs, which makes them easy to use even at home.

COVID-19 Antiviral Pills and Vaccines

One of the common questions that arose after the development of these pills is, will people still have to be vaccinated if they use these pills? It is important to realize that COVID-19 is a deadly disease, and these pills are definitely not a replacement for the vaccine.

The COVID-19 vaccine works on the prevention of the disease and protects people against the virus. On the other hand, these antiviral pills slow down the replication of the virus, making the symptoms less intense. Thus, antiviral pills slow the spread of the virus in COVID-19 patients that are more likely to develop severe symptoms.

The pills are not as effective as a vaccine because they do not provide protection from the virus. In simple words, if you have already caught the virus and have developed severe symptoms, the pills will not work for you effectively. It is because the patients are supposed to take these antiviral pills in the initial five days of being symptomatic.

If you start taking these pills after five days of catching the virus the pills won’t work effectively for you. Concluding it to the point that these antiviral pills are a development that will be beneficial in the fight against COVID-19 by working alongside preventive vaccines.

Expert Opinions on COVID-19 Antiviral Pills

According to Dr. Faheem Younus a famous M.D, the pills will still remain effective against the Omicron variant of COVID-19 contrary to the belief of some people that the new variant is resistant to the antiviral pills.

Here are the thoughts of James Adams, a medical ethicist, and professor of emergency medicine at Northwestern University, Evanston, Illinois on the COVID-19 antiviral pill Paxlovid by Pfizer:

“Speaking as a practising physician, I would look at the safety data and would consider prescribing the medication to vaccinated people who also might be at high risk. This will become very interesting. The government is bulk purchasing so might exercise control. I suspect that off-label prescribing will be strongly discouraged, but that will not stop many doctors from loudly expressing opinions and, in some cases, perhaps even gaming the system to get access for high risk but vaccinated individuals. This new drug might give comfort and confidence to those who wish to remain unvaccinated, but there will remain extraordinary medical, regulatory, and employer pressures for vaccination.”


Here’s what Dr. Albert C Shaw, MD, Ph.D. (Yale School of Medicine) had to say about Merck’s Molnupiravir pill:

“It certainly has the potential to be a really important advance. Other COVID-19 treatments, such as remdesivir or monoclonal antibodies against the SARS-CoV-2 virus causing COVID-19, are given intravenously. This is a pill your physician could write a prescription for, that you could pick up in a drugstore.”

Disclaimer: The contents of this article are intended to raise awareness about common health issues and should not be viewed as sound medical advice for your specific condition. You should always consult with a licensed medical practitioner prior to following any suggestions outlined in this article or adopting any treatment protocol based on the contents of this article.

Dr. Muhammad Asad Arshad - Author Dr. Muhammad Asad Arshad is a renowned Internal Medicine Specialist currently practicing at Ahmed Med-Surgical Center in Lahore, Pakistan.
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