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Positive test rates for COVID-19 PCR tests appear to be rising nationwide

  • April 18, 2020
  • , NHK digital , 7:55 p.m.
  • JMH Translation

The “positive test rates” for COVID-19 polymerase chain reaction (PCR) tests appear to be on the increase nationwide, NHK has found.

 

The “positive test rate” is the percentage of people tested for COVID-19 who are found to be positive.

 

NHK looked at the positive test rates released by the Ministry of Health, Labor and Welfare (MHLW) based on the reports it receives from the prefectures.

 

According to the MHLW, there are cases where the reported number of people tested does not include tests performed by private-sector screening institutions without going through a public health center. Therefore, the positive test rates are estimates.

 

The rate for Tokyo falls under this category [namely, the positive test rate does not include data from private-sector institutions].

 

The nationwide average positive test rate was 6.2% for the period from Jan. 15, when the first COVID-19 case was confirmed in Japan, through March 14. The average for the two-week period ending April 16 was 12.9%, an increase of about twofold.

 

Looking at prefectures seeing an increase in the number of COVID-19 patients:

 

Prefecture

Average positive test rate for

Jan. 15–March 14 period

Average rate for two-week period

ending April 16

Tokyo

10%

56.1% (highest in the nation)

Saitama

6.5

17.8

Ishikawa

4.7

19.8

Fukuoka

0.5

8

 

Turning to prefectures that have not released data for the Jan. 15–March 14 period:

 

Prefecture

Average positive test rate for

Jan. 15–March 14 period

Average rate for two-week period

ending April 16

Osaka

25.7%

Kanagawa

19

Chiba

15.6

 

“Number of latent patients may have increased,” expert

 

Mitsuo Kaku, a specially appointed professor in infection control science at Tohoku Medical and Pharmaceutical University, comments: “An increase in the positive test rate is thought to indicate that the number of hidden cases of infection has risen. In addition, the increase in the positive test rate is also attributed to the fact that more people are now being tested as the virus has become more widespread. If the positive test rate rises, more people will be diagnosed with COVID-19. This means a growing burden on the healthcare system. I understand that there are now cases where people cannot be tested even through a doctor has said testing is needed. To help those in serious condition, Japan needs to enhance its testing framework so that high-risk individuals, including the elderly and people who have a preexisting condition, can be given priority in testing.”

 

Positive test rate in the 13 prefectures seeing an increase in number of cases

 

Looking at the positive test rate for the 13 prefectures that are seeing an increase in COVID-19 cases:

 

Prefecture

Average positive test rate for

Jan. 15–March 14 period

Average rate for two-week period

ending April 16

Kyoto

2.7%

11.4%

Gifu

0.8

11.9

Ibaraki

0 (no cases)

5.9

 

There are also local governments that have not seen a major change:

 

Prefecture

Average positive test rate for

Jan. 15–March 14 period

Average rate for two-week period

ending April 16

Hyogo

10.3%

12.7%

Hokkaido

10.7

10.7 (no change)

Aichi

10.9

9.4

 

Hard to calculate positive test rate that includes data from private-sector screening institutions

 

The MHLW says it is receiving reports from private-sector testing organizations regarding the number of PCR tests they implement; however, the numbers include people tested more than once and the data is not broken down by prefecture. For this reason, it is difficult to calculate positive test rates that include data for people tested at private-sector screening institutions.

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