Coronavirus

Coronavirus-flu virus test kits welcomed though accuracy concerns remain

Yomiuri Shimbun file photo
A doctor uses a test kit for the simultaneous detection of the novel coronavirus and influenza viruses at a fever outpatient clinic in Saitama Prefecture.

The Yomiuri Shimbun

17:35 JST, November 29, 2022

The commercial availability of test kits for simultaneous detection of the novel coronavirus and seasonal influenza viruses is expected to reduce the pressure on outpatient fever clinics. As another winter approaches amid the threat of dual outbreaks of COVID-19 and the flu, however, there are issues to be addressed, such as concerns over the accuracy of antigen test kits.

“Allowing young people and others at low risk of developing serious illness to conduct tests themselves can prevent a situation in which an overwhelming number of patients rush to outpatient fever clinics,” said Sakuro Ando, head of Ochiai Ekimae Clinic in Tokyo.

The use of online medical examinations is a major pillar of the government’s strategy to deal with simultaneous outbreaks, and the test kits can be used as one of the factors to examine patients suspected of having the flu.

Some infectious diseases experts are concerned about the accuracy of the tests, however.

“Even for medical institutions, only about 60% are able to correctly diagnose influenza through antigen testing,” said Saitama Medical University Prof. Masafumi Seki, who is a member of the Influenza Committee of the Japanese Association for Infectious Diseases. “At home, the accuracy may drop even further if specimens are not collected correctly.”

Because influenza virus numbers are low at the onset of the flu, the kits cannot accurately determine if the patient has influenza until 12 hours after onset. The influenza drug Tamiflu must be taken within 48 hours of the onset of illness, so this treatment opportunity could be missed with a false negative result.

“Do not be relieved with a negative test result,” Seki said. “Another test or a visit to a doctor is needed if symptoms persist.”

Also unclear is whether there will be enough test kits available.

“At this point, we do not plan to make the kits available at pharmacies,” said a representative of Tokyo-based major testing agent producer Denka Co. “We are doing our best to supply the kits to medical institutions.”