Japan's Covid mystery

After writing an article about how Japan's new Covid-19 cases decreased rapidly in just a month, I got many emails from the readers. They can be summed up as "It is obvious that Japan intentionally deceased the number of Covid..

LEE YOUNG-HEE The author is a Tokyo correspondent of the JoongAng Ilbo.

After writing an article about how Japan’s new Covid-19 cases decreased rapidly in just a month, I got many emails from the readers. They can be summed up as “It is obvious that Japan intentionally deceased the number of Covid tests to shift to a ‘Living with Corona’ policy” or “It costs as much as 200,000 won ($167) to get a PCR test in Japan. Do you still want to praise Japan when you know well the situation firsthand?”

They are partly right and partly wrong. It is true that it costs 200,000 won to get a PCR test in Japan if you get tested without symptoms. But if you have symptoms and the doctor recommends the testing, or if you had close contact with the infected, you can get tested for free. Since there’s no system for anyone to get tested for free, a number of asymptomatic patients likely exist.

The number of Covid tests increased to 170,000 a day in mid-August, when 20,000 new daily cases were found. Recently, the number of tests decreased to 30,000 to 60,000 a day, except for the weekend. The number of tests has certainly decreased, but in Tokyo, the positive testing rate, which soared to 24 percent in mid-August, dropped to 1.8 percent on October 5. The positive result rate per test dropped too dramatically to say that “positive cases decreased because people don’t get tested enough.”

The problem is that no one knows the reason for the surprising drop in positive cases. Medical experts concluded that Japan’s vaccination rate increased to 77.2 percent for the first dose and 62.3 percent for the second dose as of October 6; traffic in the evening also decreased due to the explosive spread after the Olympics; and there’s the weather factor, including a late rainy season.

When they are not enough to explain the trend, a novel theory also emerged. Some experts point to the “error catastrophe theory” by 1967 Nobel Prize winning chemist Manfred Eigen. Simply put, when virus replication exceeds a certain threshold, replication failure increases and the genes needed for their own survival are destroyed. As Delta variants rapidly spread in July and August, the “limit of error catastrophe” was hit, and the number of infected fell, they argue.

Even taking this theory into account, it is mysterious that the timing for virus’s extinction coincided with the change of Japan’s administration. The Fumio Kishida government’s Covid-19 policy seems to focus more on economic recovery than prevention of the spreading. But as the spread calmed for no clear reason, expert warnings against the next spread from unexpected variants or some mysterious factors should be noted.