TOKYO/KOBE – Japan has seen a rapid increase in infections of coronavirus variants, with confirmed cases jumping 60% over a single week, complicating the work of a government scrambling to contain the pandemic ahead of the Summer Olympics.
A total of 271 cases of variant strains -- considered to be more infectious -- were confirmed in Japan as of Tuesday, according to the Ministry of Health, Labor and Welfare. This is up from 165 cases from a week ago.
An additional 74 cases of mutant strains were found through quarantine at airports. A traveler from the Philippines has been confirmed to be infected with a variant found in that country.
In countries where mutated strains have become dominant, rising hospitalizations are again testing medical facilities. Japan will try to contain the variants' spread by limiting travelers from overseas. But experts say they may already be more prevalent than documented.
The new variants' geographical reach is also expanding, with cases found in 21 out of 47 prefectures, up from 17 prefectures from the previous week.
Osaka Prefecture had the highest number of cases at 62. The British variant was by far the most common, accounting for 260 cases. The British strain is said to be 40-70% more infectious than previous versions, and one study shows that the variant is 60% more fatal.
On Friday, the health ministry reported that a man in his 60s who arrived at Tokyo's Narita Airport from the Philippines on Feb. 25 tested positive for a strain native to that country. The ministry says the strain pose roughly the same threat as the British, South African and Brazilian variants.
There have been 34 cases of the mutant virus recorded in the Philippines as of March 2, according to an announcement from the nation's Department of Health. Japan's National Institute of Infectious Diseases says the government should consider tougher border measures.
Given that newly confirmed COVID-19 cases average 1,000 a day in Japan, the number of new variant infections is still small in comparison. But experts fear that the new strains are spreading beneath the surface.
In Kobe, which is aggressively screening for variant strains, the U.K. strain accounted for 39% of new coronavirus cases detected during the week through March 4, up from 22% a week earlier.
"There's no mistaking that it is spreading," said Kobe Mayor Kizo Hisamoto.
There is a strong likelihood that some people infected with mutated strains have fallen through the cracks. A total of 1,234 coronavirus patients, or just 17.4% of the new COVID-19 cases, were screened for variants in 37 prefectures in the week through Feb. 28.
Starting this month, the screenings for mutant variants have been conducted in all prefectures. But government officials maintain the stance that the new strains have not spread broadly across the country.
But in Tokushima Prefecture, located on the island of Shikoku, nine cases of the mutant strains were reported Friday.
The variant strains "will become mainstream sooner or later," said Shigeru Omi, who heads the government's coronavirus response subcommittee.
The Brazilian strain, thought to be 40-120% more infectious, has run rampant. The country reported 2,286 coronavirus fatalities on Wednesday, the highest death count in the world, outstripping the U.S.
The British strain accounted for 54% of new Italian infections in mid-February, along with 65% of new cases in France. In Italy's Molise region, 70% of intensive care unit beds are filled. France has imposed weekend stay-at-home orders on Nice and two other areas.
Meanwhile, Japan's Transport Minister Kazuyoshi Akaba officially unveiled a plan to cap the number of people entering the country at 2,000 a day for the time being. The limit will also apply to Japanese nationals returning home.
To combat the spread of the mutant strains, Mitsuyoshi Urashima, a professor of molecular epidemiology at the Jikei University School of Medicine in Tokyo, urges the government to early preventive measures.
"There is a good chance the variants will spread through April, especially in urban areas," said Urashima. "If the [cases] grow by a large margin, there's no stopping the epidemic even if measures are taken."