Chugai Pharmaceutical on Monday asked Japan's health ministry to greenlight the expanded use of a COVID-19 antibody cocktail.
The treatment is currently authorized for use in patients with mild to moderate symptoms who are at risk of falling gravely ill.
Chugai, which has the exclusive rights to sell the drug in Japan, wants it approved for use in people without symptoms and as a measure to prevent infection.
The cocktail of two virus-neutralizing antibodies is administered intravenously. About 35,000 people in Japan are believed to have undergone the treatment as of October 5.
Chugai says a global clinical study has shown that the drug reduced the risk of asymptomatic COVID-19 patients progressing to symptomatic by 31 percent.
The study also included family members who were not infected at the start of the trial and remained in close contact with the patients. Chugai says the drug reduced their risk of symptomatic infection by 81 percent.