Fear weighs heavy on the capital, where a rise in infections has residents questioning whether the second coronavirus wave is approaching.
It’s unclear which parts of the world are emerging from a first wave or teetering on the cusp of a second. Either way, experts say distinguishing one from another will be difficult, and discerning its progression might only be possible in retrospect.
All one can do now, they say, is act on the lessons learned from the first wave and brace for more.
“We don’t even know if what happened in Japan was the first wave,” said Koji Wada, a professor of public health at the International University of Health and Welfare in Tokyo and a member of the government’s coronavirus panel.
“An outbreak could happen at any time,” he said. “The precautions we take now will determine what happens next.”
While there are no tangible criteria for declaring a second wave, the panel said earlier this month that social distancing, voluntary business closures and other countermeasures may be needed again if the infection rate for every 100,000 people exceeds 0.5 percent.
Using that math, the population of metropolitan Tokyo, which breached 14 million this month, will be dealing with a second wave when infections hit 70 a day.
The daily tally had been hovering around 40 until Wednesday, when 55 were reported. That was the first time more than 50 cases has been reported since May 5.
The metropolitan government reported 60 cases on Sunday, 57 on Saturday and 54 cases Friday.
“This does not indicate the arrival of a second wave,” Tokyo Gov. Yuriko Koike said at a news conference Friday, citing input from the city’s coronavirus panel.
Experts are hesitant to sound the alarm as well.
“I don’t believe this is a second wave, more like smoke rising from the first,” said Haruo Ozaki, chair of the Tokyo Medical Association.
“However, if Tokyo starts to report more than 100 cases a day like it was in April, there’s only so much that can be done to prevent the health care system from being stretched beyond its limits,” he said.
Speculation about the trajectory of the virus remains an unnerving affair.
Is the distinction of a second wave from the first a statistical calculation, an epidemiological observation or both? Can it only be done after a wave has come and gone? How can we tell when the next wave begins?
Hindsight will provide some knowledge of how and where the coronavirus has spread — and which countermeasures worked — but foresight is what could prevent or mitigate future outbreaks.
During Tokyo’s initial outbreak, Ozaki said the lack of intermediate housing for asymptomatic or mild patients ended up flooding hospitals with patients and straining its health care system.
In April, the metropolitan government enlisted the help of several hotels to provide housing for such patients to ease the burden. Earlier this month, it began recruiting more facilities for the same purpose in preparation for another wave.
Ozaki said the city has also made significant progress in bolstering its health care system by raising testing capacity and increasing hospital beds for coronavirus patients.
As of Saturday, the metro government had reported more than 6,000 cases and 325 deaths. Nationwide, there have been more than 18,000 cases and nearly 1,000 deaths.
The government’s panel said the outbreak peaked between April 9 and 15, when 3,800 infections emerged. In comparison, 503 cases were reported between June 20 and 26.
In mid-April, the capital reported 206 cases just 10 days after Prime Minister Shinzo Abe declared a state of emergency in seven prefectures, including Tokyo, on April 7.
While those numbers are low in comparison to other parts of the world, the threat of a bigger, more devastating second wave hangs over the country like a dark cloud.
Monitoring for signs of a second wave, as opposed to improvising a response to the initial outbreak, requires a fundamental shift in strategy, and countries around the world are implementing measures to track new cases as soon as they emerge.
Earlier this month, the government released a free smartphone application that alerts users when they may have come in close proximity with someone infected with COVID-19.
If someone using the app comes within a meter of an infected individual for 15 minutes or more, their phone records the event. If a user tests positive and records that in the app, those around them will receive a similar warning.
Until now, the government’s system for contact tracing consisted of interviews with infected patients conducted in person by public health officials. The new application could modernize that system.
Human waste could also serve as an unlikely tool in tracking the contagion in real time.
Last week, researchers from Yamanashi University and Hokkaido University announced they had successfully detected the novel coronavirus in a water sample taken from a sewage system in Yamanashi Prefecture. Similar research is underway in Tokyo and Yokohama as well as Ishikawa and Toyama prefectures.
Trace amounts of COVID-19 can sometimes be found in the stool of individuals infected with the virus — even those with no symptoms, research shows — and monitoring samples from sewers could help officials detect the virus quickly and how much it has spread within a given area.
But such measures can only prepare the country for another wave. The risk of further outbreaks will remain ever present until a sufficient treatment or vaccination is made widely available.
Last month, hints of clusters emerged in Hong Kong, Singapore, South Korea and China after citywide lockdowns were lifted. More recently, several parts of the United States are suffering the same fate.
In Tokyo, people from a wide range of age groups were swept up in the first outbreak, but officials say this recent surge involves mostly people in their 20s and 30s.
And a significant portion of new cases — around 10 percent, depending on the day — reported in Tokyo over the past week can be traced back to host and hostess bars and other nightlife destinations.
Clusters are also emerging among family members sharing a living space as well as workers using the same office building.
Experts predict that any new wave in Japan, if and when it arrives, is going to be triggered by travelers returning from abroad after border restrictions are loosened or explosive clusters surfacing among groups of young people already in the country.
In any case, they say, residents need to adopt long-term changes in their lifestyles and policymakers need to practice caution and flexibility so they can respond appropriately to whatever happens next.
“We don’t know how many waves there will be or how long this pandemic will last. Not until it’s all over,” Wada said. “Until then, the virus could spread again at any moment and we need to be ready.”
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