The emergence of SARS-CoV-2 viral variants is challenging current anti-viral and preventative strategies, including monoclonal antibodies and vaccines. Thus there is an urgent need for an easy to produce, distribute, and specific direct-acting antiviral for COVID-19 treatment to limit the progression of illness and prevent transmission.

A randomized, Phase 2 dose-range finding study investigated the efficacy of molnupiravir utilizing real-time polymerase chain reaction (RT-PCR).

Participants were categorized as having- 

• Signs/symptoms of COVID-19 in the last 7 days, and 
• SARS-CoV-2 RT-PCR positive within 4 days of enrollment. 

Originally, they were randomized in a 1:1 ratio to receive either 200 mg molnupiravir or placebo in a BD dose for 5 days. Later, for the dose-range analysis, the subjects were randomized in a 3:1 ratio to receive either 200, 400, or 800 mg molnupiravir or placebo in a BD dose for 5 days. 

175 subjects underwent nasopharyngeal swab analysis for SARS-CoV-2 infectivity at the baseline, Day 3 and 5. Vero E6 cell monolayers, infected with the sample for an hour and the culture medium was studied for viral load at 2 and 5 days post-infection by RT-PCR.

The following observations were made-

• 45% of the participants with a median of 4.62 days from symptom onset demonstrated a positive SARS-CoV-2 culture at enrollment. 
• 4% of participants on active and 28% of participants on placebo with a positive viral culture at enrollment were positive on Day 3. 
• 0% of the participants of the molnupiravir group and 24% of placebo participants were culture positive on day 5.

This study serves as the pioneer to explain the reduction in infectiousness by antiviral therapy in people with SARS-2 infection. This oral antiviral therapy will benefit mankind and is unlikely to be affected by spike-protein variants.

Source- Topics in Antiviral Medicine,2021; 29(1):304-305.