How antiviral medication stops viruses in their tracks

June 30, 2021 | by Jonathan Pinsky, MD
Categories: Healthy Driven Life

This blog was originally posted in 2021. Some information may be out of date. For the latest updates on vaccines, testing, screening, visitor policy and post-COVID support, visit

Vaccines are the best defense against COVID-19, by providing immunity that is ready to be called into action at the moment of exposure to the SARS-CoV-2 virus, before the virus has a chance to make you sick, and before you can transmit it to someone else.

Antivirals are medications given to patients already infected to slow down the virus from making more copies of itself. There are oral antivirals approved by the Food and Drug Administration (FDA) for influenza, hepatitis C virus, herpes virus and HIV, but not for SARS-CoV-2.

Existing antiviral medications for SARS-CoV-2 are all intravenous. An oral antiviral given in the first few days after the onset of symptoms could act as a rescue treatment to prevent the development of a life-threatening pneumonia and the need for hospitalization. The absence of a currently available FDA proven rescue oral treatment is yet another reason to get vaccinated.

What are the existing anti-viral treatments for COVID-19?

Convalescent plasma

The earliest studies used plasma donated from patients who recovered from COVID-19, called “convalescent plasma,” that contain antibodies which bind the virus, preventing cellular invasion.  Convalescent plasma was not found to be beneficial for most hospitalized patients, who typically present at a later stage of infection, too late for the treatment to be effective.

Monoclonal antibodies

Antibodies of one or more types manufactured synthetically given to non-hospitalized patients with mild or moderate symptoms, early in the course of infection, shorten the duration of illness and decrease the chance of needing hospitalization. Monoclonal antibodies are approved under FDA Emergency Use Authorization for patients with COVID-19 who have medical conditions that put them at high risk.


Remdesivir, first developed in 2009 as a possible hepatis C drug, inhibits viral enzymes responsible for replication. In 2017 it was found to have activity against a wide range of RNA viruses, including Ebola and the coronaviruses: Middle East respiratory syndrome (MERS) and severe acute respiratory syndrome (SARS). When COVID-19 emerged, research quickly took off into using remdesivir against SARS-CoV-2.

In two large phase 3 trials in the United States, remdesivir given intravenously to patients hospitalized for COVID-19 was found to improve the time to resolution of symptoms, decrease the number of days of hospitalization, and reduce mortality for a subgroup of patients with lung inflammation and in need of modest levels of oxygen support.

What are the antiviral medications under investigation?


In 2003, an intravenous predecessor of molnupiravir was developed. This compound acts as a nucleoside analog, stopping viral replication. The compound was active against hepatis C, influenza, and the MERS and SARS coronaviruses.

In 2013, researchers looking for a treatment for Venezuelan equine encephalitis virus changed the chemical structure into a form that can be absorbed through the gastrointestinal tract, and then converted into the active drug inside cells.

Research into oral molnupiravir began in 2019 for pandemic influneza, but then quickly shifted to COVID-19. Molnupiravir given to patients with COVID-19 infections was found to effectively diminish the time of viral shedding. Two phase 3 studies began, one for hospitalized and the other for non-hospitalized patients. The inpatient part of the study was stopped due to a lack of evidence for clinical improvement in patients with a longer duration of symptoms. Thousands of patients will be enrolled in the outpatient study, testing the effectiveness of molnupiravir, given to patients with symptoms for 5 days or less. Results are expected in fall 2021.

Another antiviral compound, “tempol,” is being investigated as a possible drug for COVID-19.

In June 2021, the U.S. government announced it was investing more than $3 billion to study, develop and manufacture antiviral medication to fight COVID-19.

Vaccines are the best weapon against COVID-19, providing protection before the virus has a chance to infect you and before it has a chance to spread to someone else.

With over 70% of eligible DuPage County residents having had at least one dose of vaccine and the majority fully vaccinated, the number of new cases is vanishingly low, making exposures less likely.

Yet, COVID-19 cases are surging across the globe in regions that do not yet have access to widespread vaccination. This coming fall and winter we may to continue to have sporadic outbreaks of COVID-19 in unvaccinated persons an in under vaccinated communities. Oral antivirals may be life-saving, especially in areas of the world that do not have access to intravenous treatments or to hospital resources. 

Edward-Elmhurst Health now has COVID-19 vaccine appointments available to anyone in our communities age 12 and older. It is easy to schedule a vaccine appointment. You no longer need a MyChart account. Schedule your COVID-19 vaccine now.

The information in this article may change at any time due to the changing landscape of this pandemic. Read the latest on COVID-19.

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