Molnupiravir May Be Effective Against COVID-19 in Vaccinated, Unvaccinated Adults

Molnupiravir may have antiviral activity against a broad range of COVID-19 variants in vaccinated and unvaccinated adults, but the evidence is inconclusive.

Molnupiravir may have antiviral activity against COVID-19 infection among both vaccinated and unvaccinated adults infected with a variety of SARS-CoV-2 variants, according to study findings published in the Lancet Infectious Diseases.

Researchers conducted a randomized, double-blind, placebo-controlled, phase 2 trial between November 2020 and March 2022 across 5 sites in the United Kingdom. They evaluated treatment responses among 180 adults patients (57% women) with polymerase chain reaction (PCR)-confirmed COVID-19 infection who were randomly assigned to receive standard care in addition to either molnupiravir or placebo within the first 5 days of infection onset. The primary endpoint was the time between treatment allocation and receipt of a negative test result for SARS-CoV-2 on PCR testing.

Among patients included in the molnupiravir (n=90) and placebo (n=90) groups, the median age was 45 (IQR, 31-55) and 43 (IQR, 28-54) years, 58% and 57% were women,  81% and 87% were White, and the median time between symptom onset and treatment allocation was 3.5 (IQR, 3.0-4.0) and 3.0 (IQR, 3.0-4.0) days, respectively. Overall, the majority of patients were infected with either the Alpha (B.1.1.7) or Delta (B.1.617.2) variants (21% and 40%, respectively), and 50% of patients had previously received at least 1 COVID-19 vaccine dose.

Researchers found that the time between treatment allocation and receipt of a negative PCR test result was decreased among patients who received molnupiravir vs placebo (median, 8 vs 11 days; hazard ratio [HR], 1.30; 95% CI, 0.92-1.71; P =.074). However, treatment with molnupiravir did not reach the 80% threshold defined a priori for progression to clinical evaluation.

molnupiravir has a moderate antiviral effect, but our evidence is not conclusive.

After 5 days of treatment, a significantly greater reduction in mean viral titers was observed among vaccinated patients in the molnupiravir group vs vaccinated patients in the placebo group (5.4 vs 4.1 log10 copies; P =.027). For unvaccinated patients, the mean reduction in viral titers at this time was 4.2 log10 copies per reaction among those in the molnupiravir group compared with 3.6 log10 copies per reaction among those in the placebo group (P =.38).

After 29 days, 81% of patients in the molnupiravir group and 76% of those in the placebo group experienced at least 1 adverse event. The occurrence of severe adverse events was decreased among patients who received molnupiravir (n=1) compared with those who received placebo (n=3). Of note, no patient in either group died during the duration of the study.

This study was limited as SARS-CoV-2 viral cultures were not obtained, and the diagnostic tools used in the analysis had inadequate sensitivity for detecting small changes in virologic efficacy conferred by molnupiravir treatment.

According to the researchers, “molnupiravir has a moderate antiviral effect, but our evidence is not conclusive.”

Disclosures: Some authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.

This article originally appeared on Infectious Disease Advisor

References:

Khoo SH, FitzGerald R, Saunders G, et al. Molnupiravir versus placebo in unvaccinated and vaccinated patients with early SARS-CoV-2 infection in the UK (AGILE CST-2): a randomised, placebo-controlled, double-blind, phase 2 trial. Lancet Infect Dis. Published online October 19, 2022. doi:10.1016/S1473-3099(22)00644-2