Photo/Illutration Takaji Wakita, the head of the National Institute of Infectious Diseases and the chair of the expert panel advising the health ministry on coronavirus countermeasures, speaks at a news conference in Tokyo on March 9 after the meeting. (Kai Ichino)

Health experts are cautioning that daily COVID-19 cases have been increasing in some of the areas where pre-emergency measures have been lifted--and that may just be the beginning.

An expert panel that advises the health ministry on coronavirus countermeasures raised concerns about the trend at its meeting on March 9, warning there could be another wave of infections sooner rather than later.

Panel members said they are concerned about the prevailing Omicron variant in Japan being replaced with the more contagious BA.2 “stealth” Omicron subvariant.

And the upcoming busy period in spring, which accompanies the end of the fiscal year when many people move, could make for the perfect storm.

“This could cause a resurgence in infections,” said Takaji Wakita, the head of the National Institute of Infectious Diseases (NIID).

The number of new cases in Japan per 100,000 people over the past week stood at 329.02, representing 90 percent of the figure of the previous week.

The overall downward trend in daily cases has held across all age groups.

But 15 prefectures reported more COVID-19 cases than the previous week.

Those include some prefectures where pre-emergency measures were lifted on Feb. 20, such as Yamagata, Shimane, Yamaguchi and Okinawa, along with other prefectures where the same measures were removed on March 6, such as Fukushima and Kochi.

The institute estimates that the BA.2 subvariant could account for 78 percent of all cases by the first week of April.

Hiroshi Nishiura, a professor of environmental hygienics at Kyoto University, calculated the subvariant’s effective reproduction number, a key indicator that shows how many people on average one carrier will infect.

He said the BA.2’s effective reproduction number is 26 percent higher than the previous Omicron variant.

The expert panel has pointed out for some time now that while many seniors died during the sixth wave, they did not develop serious symptoms related to COVID-19 and some had died due to pre-existing conditions that had worsened.

At the meeting, the panel reported specific data detailing that trend.

Research conducted by the Kanagawa prefectural government revealed that of about 310 COVID-19 patients who died between January and February, 98 percent were those aged 60 or older.

According to the report, in 53 percent of the deaths, the main cause of death stemmed from COVID-19. But the remaining 47 percent are attributable to other causes, such as old age, or unknown reasons. 

Breaking down the data by severity of symptoms, patients with moderate symptoms accounted for the highest at 57 percent of all the deaths.

According to research done by the Okayama prefectural government, during the fourth wave, 99 percent of all deaths of patients infected with the novel coronavirus were related to COVID-19. But that figure dropped to 68 percent during the sixth wave.

Of the COVID-19 patients who died, 79 percent were previously hospitalized at medical institutions or had stayed at elderly care facilities before they became infected with the virus.

For the first time, the fatality rates from the Omicron variant, broken down by age group, were publicly reported by the heads of nine public health centers and other officials.

Those rates rose markedly with age. Within 20 days of diagnosis, the figures were 0.0228 percent for people in their 40s, 0.0178 percent for those in their 50s, 0.124 percent for those in their 60s, 0.579 percent for those in their 70s, 2.13 percent for those in their 80s, and 3.43 percent for those 90 or older.

(This article was written by Yuki Edamatsu and Kai Ichino.)

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