Some Japanese Municipalities Adopt ‘PCR Pool Testing’

The Yomiuri Shimbun
A man hands in his sample at a PCR test facility in Nasushiobara, Tochigi Prefecture on Jan. 26.

Some local governments have introduced a new way of testing for the novel coronavirus, in which samples from several people are mixed and tested at once.

While this approach enables quick, efficient detection of asymptomatic infected people at low cost, the pooled testing system has problems in accuracy, and it requires reexamination on an individual basis when positive results are obtained. Still, the system is likely to spread as it was approved by the Health, Labor and Welfare Ministry in January for use in government-funded administrative inspection of employees at nursing care facilities, among others.

A 70-year-old company owner in Nasu-Shiobara, Tochigi Prefecture, handed in a test kit containing his own and his wife’s saliva, and paid ¥1,000 as the household test fee at a PCR test facility set up in a prefabricated building in the city’s Shimakata district on Jan. 26. The test results would be available in a few days.

“Since my wife often goes to Tokyo, we took this test to ease our concerns. We appreciate an opportunity like this,” he said.

On Jan. 12, the city started accepting applications for the municipal initiative’s pool testing. Up to five people can take a test per household, at an actual cost of ¥5,500 per household. The city government covers the difference between the total fees and the ¥1,000 paid by each household taking the test. There were 904 applications for the test as of Feb. 1, and the testing center was fully booked for days.

The city expects to inspect samples from about 2,500 households by the end of March. “The number of those who took the test is increasing steadily, and some citizens want to have a second test,” a city official said.

On Jan. 13, Tokyo’s Setagaya ward government began pool testing on 15,400 people working at nursing homes and facilities for the disabled. The municipality was able to do so before the test was recognized for administrative inspection purposes by the central government thanks to the Tokyo metropolitan government’s subsidies.

A company entrusted by the ward government uses saliva collected by the examinees themselves for the test, in which up to four people can be examined at a time. The method is said to reduce the cost of reagents by about 75%.

The Hiroshima prefectural government also plans to conduct pool testing sometime after mid-February. The city government of Funabashi, Chiba Prefecture, is also considering introducing such test.

On Jan. 22, the health ministry presented local governments with guidelines for implementing the pool system.

The ministry initially did not approve the test, as it was unable to confirm the accuracy of the data. But the ministry is believed to have found that the test can be effectively used.

According to the guidelines, the test should be conducted on groups of five people in principle, mainly employees and residents of nursing care facilities and medical facilities where no positive cases have been confirmed. It must be noted, however, that the accuracy of the test can be low because of the mixing of samples, and it takes time to retest examinees if a high positive rate is found among them.

Tokai University Prof. Hayato Miyachi, a laboratory medicine expert, said: “The pooling method is effective for testing large numbers of asymptomatic people because the cost is low. It is necessary, however, to manage the inspection system to prevent mix-up and other mistakes.”