KYODO NEWS - Apr 22, 2020 - 16:15 | All, Japan, Coronavirus

The Japanese health ministry is considering introducing an antigen test to more quickly screen for the new coronavirus amid a rise in the number of people who need testing, government sources said Wednesday.

The ministry may approve an antigen test kit that uses mucus taken from nose in May. But as the new test is less precise than the existing polymerase chain reaction test, the dominant testing method which takes hours before results come out, officials will study under what circumstances to use it, they said.

(A mock drive-through coronavirus testing is carried out in Nara, western Japan, amid the spread of the pneumonia-causing virus.)

The antigen test detects protein unique to the virus and does not need to be conducted at labs like the PCR test, which involves amplifying small amounts of DNA sequences of the virus, a process that conventionally requires four to six hours to produce a result.

While methods to shorten the length of the PCR test to about an hour have been developed, there is a growing demand for a simpler and quicker test as the number of people who need to undergo the test has surged in parts of Japan amid the epidemic.

An antibody test is also considered a quick testing method but it requires antibodies to build up in a person, meaning it takes time before people start testing positive after becoming infected with the virus.

A number of companies have developed test methods to speed up PCR tests, including Toyobo Co. and Shimadzu Corp., which have both released testing kits.

The government sources said private firms have been developing antigen test kits and are expected to release them soon. The ministry is seeking to approve such kits as a medical device in May at the earliest.

Yokohama City University has also developed a substance that helps detect the virus, and is seeking to develop in about two months a kit that can obtain results in 15 to 30 minutes.

As the antigen test is considered to have lower sensitivity to the virus than the PCR test, the quick method is likely to be used for patients in serious condition who must receive treatment as soon as possible rather than people with minor or no symptoms and a smaller amount of virus in their body.