Healthcare
Visualizing How COVID-19 Antiviral Pills and Vaccines Work at the Cellular Level
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Current Strategies to Tackle COVID-19
Since the pandemic started in 2020, a number of therapies have been developed to combat COVID-19.
The leading options for preventing infection include social distancing, mask-wearing, and vaccination. They are still recommended during the upsurge of the coronavirus’s latest mutation, the Omicron variant.
But in December 2021, The United States Food and Drug Administration (USDA) granted Emergency Use Authorization to two experimental pills for the treatment of new COVID-19 cases.
These medications, one made by Pfizer and the other by Merck & Co., hope to contribute to the fight against the coronavirus and its variants. Alongside vaccinations, they may help to curb extreme cases of COVID-19 by reducing the need for hospitalization.
Despite tackling the same disease, vaccines and pills work differently:
Vaccines | Pills |
---|---|
Taken by injection | Taken by mouth |
Used for prevention | Used for treatment only |
Create an enhanced immune system by stimulating antibody production | Disrupt the assembly of new viral particles |
How a Vaccine Helps Prevent COVID-19
The main purpose of a vaccine is to prewarn the body of a potential COVID-19 infection by creating antibodies that target and destroy the coronavirus.
In order to do this, the immune system needs an antigen.
It’s difficult to do this risk-free since all antigens exist directly on a virus. Luckily, vaccines safely expose antigens to our immune systems without the dangerous parts of the virus.
In the case of COVID-19, the coronavirus’s antigen is the spike protein that covers its outer surface. Vaccines inject antigen-building instructions* and use our own cellular machinery to build the coronavirus antigen from scratch.
When exposed to the spike protein, the immune system begins to assemble antigen-specific antibodies. These antibodies wait for the opportunity to attack the real spike protein when a coronavirus enters the body. Since antibodies decrease over time, booster immunizations help to maintain a strong line of defense.
*While different vaccine technologies exist, they all do a similar thing: introduce an antigen and build a stronger immune system.
How COVID Antiviral Pills Work
Antiviral pills, unlike vaccines, are not a preventative strategy. Instead, they treat an infected individual experiencing symptoms from the virus.
Two drugs are now entering the market. Merck & Co.’s Lagevrio®, composed of one molecule, and Pfizer’s Paxlovid®, composed of two.
These medications disrupt specific processes in the viral assembly line to choke the virus’s ability to replicate.
The Mechanism of Molnupiravir
RNA-dependent RNA Polymerase (RdRp) is a cellular component that works similar to a photocopying machine for the virus’s genetic instructions. An infected host cell is forced to produce RdRp, which starts generating more copies of the virus’s RNA.
Molnupiravir, developed by Merck & Co., is a polymerase inhibitor. It inserts itself into the viral instructions that RdRp is copying, jumbling the contents. The RdRp then produces junk.
The Mechanism of Nirmatrelvir + Ritonavir
A replicating virus makes proteins necessary for its survival in a large, clumped mass called a polyprotein. A cellular component called a protease cuts a virus’s polyprotein into smaller, workable pieces.
Pfizer’s antiviral medication is a protease inhibitor made of two pills:
- The first pill, nirmatrelvir, stops protease from cutting viral products into smaller pieces.
- The second pill, ritonavir, protects nirmatrelvir from destruction by the body and allows it to keep working.
With a faulty polymerase or a large, unusable polyprotein, antiviral medications make it difficult for the coronavirus to replicate. If treated early enough, they can lessen the virus’s impact on the body.
The Future of COVID Antiviral Pills and Medications
Antiviral medications seem to have a bright future ahead of them.
COVID-19 antivirals are based on early research done on coronaviruses from the 2002-04 SARS-CoV and the 2012 MERS-CoV outbreaks. Current breakthroughs in this technology may pave the way for better pharmaceuticals in the future.
One half of Pfizer’s medication, ritonavir, currently treats many other viruses including HIV/AIDS.
Gilead Science is currently developing oral derivatives of remdesivir, another polymerase inhibitor currently only offered to inpatients in the United States.
More coronavirus antivirals are currently in the pipeline, offering a glimpse of control on the looming presence of COVID-19.
Author’s Note: The medical information in this article is an information resource only, and is not to be used or relied on for any diagnostic or treatment purposes. Please talk to your doctor before undergoing any treatment for COVID-19. If you become sick and believe you may have symptoms of COVID-19, please follow the CDC guidelines.
Healthcare
Innovation in Virology: Vaccines and Antivirals
Vaccine development has grown six-fold since 1995. Learn how virology, the study of viruses, is driving innovation in the healthcare industry.

Innovation in Virology: Vaccines and Antivirals
The COVID-19 pandemic affected millions of people worldwide and brought renewed focus to virology—the study of viruses.
However, impact made by viruses extends far beyond the SARS-CoV-2 virus that causes COVID-19. There are 24 viruses that have each infected more than 80 million people globally, from hepatitis to influenza.
In this graphic from MSCI, we uncover innovation in vaccines and antivirals and the related market opportunities.
What is a Virus?
A virus is a microscopic infectious agent that replicates within living cells. It may cause disease in its host. New viruses can emerge at any time as a result of mutation, or when viruses transfer from animals to humans.
Through virology, scientists are continuously finding new ways to fight against infectious diseases. Two main types of anti-infectives are available: vaccines and antivirals.
Rapid Innovation in Vaccines
Vaccines are substances designed to prevent people from getting infected with a disease or experiencing serious symptoms.
The number of vaccines has increased dramatically over the last three decades. From 2020 to 2021 alone, the number of approved vaccines or clinical candidates jumped by 13%.
Year | Vaccines Approved or in Development |
---|---|
1995 | 240 |
1996 | 262 |
1997 | 309 |
1998 | 323 |
1999 | 374 |
2000 | 415 |
2001 | 462 |
2002 | 472 |
2003 | 509 |
2004 | 531 |
2005 | 564 |
2006 | 610 |
2007 | 606 |
2008 | 704 |
2009 | 751 |
2010 | 866 |
2011 | 893 |
2012 | 880 |
2013 | 943 |
2014 | 1075 |
2015 | 1179 |
2016 | 1374 |
2017 | 1397 |
2018 | 1340 |
2019 | 1356 |
2020 | 1388 |
2021 | 1567 |
Data is a snapshot in time and reflects all vaccines ever approved (and not taken off the market) plus all vaccines in development as of the noted year (for which a trial has not been canceled).
Not only that, it’s possible to have shorter approval timelines. COVID-19 vaccines were approved within 11 months, much more quickly than the 2000-2020 average of 10 years.
In the time between an outbreak and vaccine development, antivirals can play a vital role.
Antivirals: The Second Line of Defense in Virology
Antivirals are drugs that slow or prevent the growth of a virus and treat disease symptoms. They are especially important tools for diseases that do not have an associated vaccine.
In 2021, there were nearly six times as many approved antivirals as there were in 1995. Not only that, antiviral uses have grown to include the potential prevention and treatment of HIV, COVID-19, and a number of other diseases.
Year | Approved Antivirals in the U.S. | Reasons for Using Antivirals |
---|---|---|
1995 | 10 | 12 |
1996 | 10 | 12 |
1997 | 12 | 12 |
1998 | 13 | 13 |
1999 | 16 | 13 |
2000 | 18 | 13 |
2001 | 19 | 13 |
2002 | 20 | 13 |
2003 | 21 | 13 |
2004 | 21 | 13 |
2005 | 22 | 13 |
2006 | 23 | 13 |
2007 | 24 | 13 |
2008 | 26 | 13 |
2009 | 27 | 14 |
2010 | 27 | 14 |
2011 | 30 | 14 |
2012 | 30 | 15 |
2013 | 34 | 15 |
2014 | 37 | 15 |
2015 | 41 | 16 |
2016 | 44 | 16 |
2017 | 47 | 16 |
2018 | 49 | 17 |
2019 | 49 | 17 |
2020 | 53 | 19 |
2021 | 57 | 20 |
The potential prevention (prophylaxis) and treatment of the same virus are counted as separate uses. Data is cumulative and reflects all antivirals ever approved (and not taken off the market) and all reasons ever approved for using antivirals (that have not been rescinded).
Innovation in virology—and the potential for future developments—is leading to a growing industry.
Expanding Market Opportunities
With opportunities growing and approval times shortening, more companies are entering the market.
Year | Companies Developing Vaccines/Antivirals |
---|---|
1995 | 66 |
1996 | 73 |
1997 | 80 |
1998 | 81 |
1999 | 87 |
2000 | 111 |
2001 | 125 |
2002 | 140 |
2003 | 154 |
2004 | 144 |
2005 | 146 |
2006 | 163 |
2007 | 167 |
2008 | 196 |
2009 | 203 |
2010 | 230 |
2011 | 237 |
2012 | 255 |
2013 | 277 |
2014 | 289 |
2015 | 310 |
2016 | 362 |
2017 | 392 |
2018 | 374 |
2019 | 370 |
2020 | 383 |
2021 | 484 |
Data is a snapshot in time and reflects all companies developing vaccines or antivirals as of the noted year. If a company stops being active in the space or ceases to exist, they are removed from the total.
As they work to develop new vaccines and antivirals, companies are conducting clinical trials for many diseases beyond COVID-19 such as respiratory infections and sepsis.
Virology is leading to a number of groundbreaking technologies and therapies, transforming healthcare along the way.

Explore the MSCI Virology Index now.

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