TOKYO — Antibody drugs that help prevent a virus from sticking to cells may be less effective for the omicron variant of the coronavirus than for the delta strain, according to a study by a team from the Institute of Medical Sciences in Tokyo. the University of Tokyo and the National Institute of Infectious Diseases. find.

At the same time, the researchers found that antiviral drugs that prevent viral reproduction inside the body showed roughly the same effectiveness for both variants. Their findings were published online in the January 26 edition of the New England Journal of Medicine.

The team led by Yoshihiro Kawaoka, a project professor of virology at the University of Tokyo, used cultured cells to test the effectiveness of existing drugs to treat COVID-19. The antibodies prevent the virus from sticking to cells and help prevent viral reproduction, and in Japan the antibody cocktail Ronapreve and the neutralizing antibody sotrovimab (brand name Xevudy) have been approved.

The result showed that the effectiveness of Ronapreve in preventing omicron from reproducing was 1/5,261 or less compared to its effectiveness against the delta variant. Sotrovimab was about two-thirds less effective against omicron than delta.

Antiviral drugs, on the other hand, interfere with the function of an enzyme that the virus needs to multiply once it enters the body. The oral drug molnupiravir is one such drug recently approved in Japan.

In the experiment, molnupiravir and intravenously administered remdesivir (also approved in Japan) would have prevented the reproduction of delta and omicron about equally.

As omicron spreads rapidly around the world, a selection of effective drugs is essential to ease the pressure on medical care providers. Kawaoka told the Mainichi Shimbun: “Regarding the antibodies, we believe that it has become difficult for the antibody agent to bind to the spike protein on the surface of the virus due to the multiple mutations of the omicron variant. There is a need to carefully determine efficacy in clinical settings.”

(Japanese original by Ayumu Iwasaki, Department of Science and Environmental News)