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Organisers in Japan are under pressure to cancel the Paralympics as another wave of COVID-19 rips through the population.
Daily new cases in Japan have soared to almost 20,000, the highest figure since the pandemic began and five times the figure when the Olympics started in the last week of July.
Tokyo hosted a majority of the events and, alongside top holiday destination Okinawa, has experienced the fastest increase in case rates.
But are the Olympics the reason for rising case numbers in Japan?
A new variant
Many health experts called for the Olympics to be cancelled over fears that it would become a superspreader event.
But when it comes to infections at the event itself, that is not borne out in the numbers. Fewer than 550 of the 80,000 athletes, officials and contractors tested positive, representing a tiny fraction of the 170,000 COVID-19 cases identified in Japan during the Games.
There are still concerns about the fallout from the Olympics, however, after it was confirmed that one person travelling from Peru to work at the event imported the more transmissible South American Lambda variant into Japan.
Akira Nishizono, professor of microbiology at Oita University, voiced his concerned about the spread of the new variant, saying that "sooner or later" Lambda will become the dominant strain in Japan.
Messaging and behaviour
The Olympics is also thought to have indirectly caused infections to rise.
Kentaro Iwata, an infectious disease expert at Kobe University, says that the Games contributed to the spread of the virus by muddling the government message around COVID-19.
"We lost the opportunity to discourage people from risky behaviour because TV/radios always talked about the Olympics instead," he said.
The data does show a notable spike in visits to retail and recreation venues at the start of the Olympics across most of Japan. Although, the trend is less pronounced in Tokyo, perhaps due to more stringent restrictions over this period.
There was also an uptick in mobility in people's homes, which may suggest that people were socialising more indoors.
While the Japanese population is generally law abiding, compliance with coronavirus restrictions appears to have waned in recent weeks.
Local media has reported that bars and restaurants defied restrictions during the event. One Tokyo izakaya owner told the Japan Times that he planned to serve alcohol despite a ban because he was fed up with the public "being sacrificed for the Olympics".
Is Delta the reason that infections are rising?
Another explanation put forward for the rapid spread of the virus is the impact of the Delta variant.
Since the first case was recorded in May, the variant has spread rapidly through the Japanese population. Around the time that the Olympics began it accounted for the majority of the country's infections.
It is difficult to distinguish between the impact of Delta and the Olympics, but health experts believe that the variant has played a critical role in the rampant spread of the virus.
Andrew Nelson, a pathologist at the University of Minnesota, says the rapid spread of Delta is "likely driving" the soaring case rates in Japan, which are "tracking similarly to all of Asia".
What can we learn from who is being infected?
In the aftermath of the Euros, the UK saw a spike in infections among younger men, which scientists have since linked to increased socialising around the event.
We can now see a similar trend in Japan, with COVID-19 cases skewing much younger than they did during earlier waves.
Professor Nishizono says this likely reflects increased socialising among younger generations in recent weeks.
There is another explanation for this trend, which is that higher vaccine coverage among older people is protecting them from infection. But Japan has been relatively slow in its vaccine rollout - only 40% of the population have received both doses.
The impact of rising infections
It is difficult to say if it is Delta or the Olympics driving the high case rates in Japan at the moment. But, whatever the cause, rising infections are placing tremendous pressure on the country's healthcare system.
Hospital bed occupancy in Tokyo is rising rapidly and currently stands at 53% for COVID-19 patients.
While occupancy levels are currently below their January peak, health experts caution about the current trajectory.
"We will see wards full soon," said Professor Iwata from Kobe University. "Okinawa already lost the game. Tokyo will follow soon."
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