Photo/Illutration A room at a Saga hospital for COVID-19 patients who develop severe symptoms (Asahi Shimbun file photo)

Japan's second wave of COVID-19 may have already peaked in late July, according to an advisory board to the health ministry.

The board of experts on infectious diseases concluded at a meeting on Aug. 24 that there has been a gradual decline in new cases this month.

At the same time, the panel noted that some regions have witnessed an increase in patients who develop severe symptoms, leading the experts to urge continued vigilance against a spread of infections.

A government panel of experts reached a similar view about the peak in new infections during its meeting on Aug. 21.

The advisory board noted that in many regions the so-called effective reproduction number, which shows how many people a COVID-19 patient has infected, fell under one in early August, meaning infections were not spreading in those regions.

But the panel also pointed out the number was still close to one, so there is a possibility of another spread in infections if areas where there are many cases end requests to businesses to shorten hours or temporarily close operations.

The panel analyzed case numbers by the day on which symptoms arose rather than when confirmed test results were reported. Based on that analysis, the panel found the peak in new cases came between July 27 and 29. The number of new cases has been declining since.

Among the reasons given for that trend are requests from prefectural governments to local residents asking them to refrain from nonessential outings, a change in activities by residents and adherence to local government requests by bars and restaurants to implement stricter measures to prevent a spread of infections.

As a result, the national total of new cases decreased by about 1,400 for the week ending on Aug. 14 in comparison with the previous week.

However, Takaji Wakita, the head of the National Institute of Infectious Diseases, who chairs the advisory board, pointed out that while a peak may have occurred, there were still no signs that the second wave had been brought under control.

Caution was urged because of the increase in patients with severe symptoms in such prefectures as Osaka, Okinawa, Aichi and Fukuoka. A similar increase occurred between March and May after the peak in the first wave of infections had passed.

“There is a need to continue with various measures until there is a decrease in patients with severe symptoms,” said Yasutaka Mizuno, who heads the Global Healthcare Clinic in Tokyo, and is knowledgeable about infectious diseases.

He added that the number of new cases would likely remain at similar levels as now for the time being and pointed to the need for monitoring new cases at various points in time, such as the resumption of school classes and the extended weekend holiday in September.

Motoi Suzuki, who heads the Infectious Diseases Surveillance Center of the National Institute of Infectious Diseases, reported on the fatality rates for people infected with COVID-19.

He said that if the first wave was defined as the period from January to May and the second wave as the period thereafter, the fatality rate for the second wave was 4.7 percent, or 1.3 percentage points lower than the first wave.

There was no major change in the fatality rate for patients aged 70 or older.

But when fatality rates were compared for those with COVID-19 and all other forms of pneumonia, those 70 or older with COVID-19 were four times more likely to die than those with other kinds of pneumonia. There was no major difference in the fatality rates of those under 70.

(This article was written by Naoyuki Himeno and Yuko Matsuura.)

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