Researchers reported that the drug molnupiravir is safe, well tolerated, and effective in patients who are at a high risk of developing severe COVID symptoms such as pulmonary fibrosis, according to a letter to the editor published in the Irish Journal of Medical Science. 

The SARS-CoV-2 pandemic has resulted in the development of related vaccines at an unparalleled speed. In addition, medical researchers have attempted to develop effective therapeutics for patients who have contracted the virus. 

The drug molnupiravir was approved for use by the Italian Medicines Agency on December 30, 2021 for treating patients with COVID who are at risk of developing severe disease. Examples of severe disease include cardiopulmonary disease, chronic renal failure, uncontrolled diabetes mellitus, and primary/acquired immunodeficiency. 

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Molnupiravir is a prodrug metabolized to the ribonucleoside analog N-hydroxycytidine (NHC), which is phosphorylated in cells to form the pharmacologically active ribonucleoside triphosphate (N-hydroxycytidine triphosphate, NHC-TP). 

“Incorporating NHC-TP into viral RNA by the use of viral RNA polymerase causes an accumulation of errors in the viral genome, which inhibits its replication,” the authors of the letter wrote. 

The clinicians reported their experience prescribing the drug to a total of 74 patients between the ages of 26 and 96 who were followed-up for a total of 30 days. Among the 74 patients, 70 were vaccinated in the 6 months before testing positive for COVID; among these 70 patients, 65 had undergone a complete vaccination course (receiving 3 doses). 

None of the patients presented with a regression of symptoms upon follow-up, and none were hospitalized and/or showed sequelae after COVID infection. This is despite the patient population being older (the average age was 72.3) and presenting with more comorbidities than patients who were treated with other available antivirals. 

“According to these results, molnupiravir can lead to a potential risk reduction of 100%, especially when associated with vaccination,” the authors of the letter wrote. 


Scioscia G, De Pace CC, Giganti G, et al. Real life experience of molnupiravir as a treatment of SARS-CoV-2 infection in vaccinated and unvaccinated patients: a letter on its effectiveness at preventing hospitalizationIr J Med Sci. Published online December 1, 2022. doi:10.1007/s11845-022-03241-1