With nations around the world struggling to deal with new variants, the Japanese government is urgently trying to establish systems for quickly detecting infections at borders and elsewhere in the country.
On Monday, a coronavirus variant prevalent in Britain was confirmed in three people from Shizuoka Prefecture who had not spent time in the country.
The Shizuoka prefectural government independently issued an emergency infection alert on Tuesday. "We can't keep acting as we have been," Shizuoka Gov. Heita Kawakatsu said at a press conference on the day.
The three confirmed cases had not had contact with large numbers of the general public and close contacts have been identified, according to prefectural sources and others.
However, if cases were to increase, it would put even more pressure on the prefecture's medical system.
Kawakatsu stressed that he would like to "suppress the chain of infections" by strengthening cooperation with the national government, and he called on prefecture residents to avoid dining with people other than their household members, unnecessary outings and travel across prefectural borders, among other measures.
-- 1.7 times more contagious
The variant identified in Shizuoka was first confirmed in Britain in autumn last year. Since then, other variants have been discovered in South Africa and Brazil.
Countries around the world are on high alert as new variants could be more contagious. The British variant is estimated to be up to 1.7 times more contagious than the unmutated form of the virus.
Viral loads from patients infected with the British variant were 10 to 100 times higher, according to a team of U.K. scientists.
A research team from Israel and other countries reported that the British variant binds to human cells 3.5 times more firmly than the original form. When combined with the South African and Brazilian variants, it is about 13 times stronger.
It is unknown whether the risk of severe disease is higher with the variants. However, a rapid increase in infections would likely lead to more deaths.
The effectiveness of vaccines is also a concern.
According to U.S. pharmaceutical giant Pfizer Inc., the results of an experiment using blood from people who had received its vaccine appear to indicate that it is effective against the British variant.
However, countries will be forced to rethink their inoculation strategies if vaccines prove to be less effective when multiple variants are prevalent at the same time.
-- Swift detection
How should Japan prepare for the spread of such variants? Experts have stressed the importance of swift detection.
The government suspended entry for new foreign arrivals from Britain and South Africa on Dec. 26. Returning Japanese citizens who tested negative at airport quarantine stations were asked to stay at designated accommodation facilities and get retested three days later.
Since Dec. 28, the entry of all nonresident foreigners has been suspended, and returnees have been asked to provide information about their location information as required.
However, there is a possibility that travelers infected with the variant got through quarantine before border rules were tightened.
"The border measures should be continued for at least a month or two," said immunology specialist Prof. Koetsu Ogasawara of Tohoku University.
Ogasawara also stressed the importance of domestic testing: "It is also possible that a Japanese mutation will emerge due to the increasing number of infections in the country," he said.
-- Testing capacity
The National Institute of Infectious Diseases is checking for variants among virus samples taken from all infections confirmed at airport quarantine and some domestic cases.
The Shizuoka infections were found during such checks.
However, only the institute and some local public medical laboratories can perform these tests. The analysis takes about two weeks and detection is not possible with small viral samples.
As of December, the institute had analyzed about 10% of virus cases nationwide. However, the recent surge in cases means the proportion is now thought to be only about 4%.
The institute is developing a rapid testing method which it aims to make available to regional medical laboratories and other health care facilities nationwide.
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