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AI predicts 370 COVID daily cases in Tokyo at 6th wave peak, but experts urge caution

Tourists flock to Komachi-dori street on the first weekend after the coronavirus state of emergency was lifted, in Kamakura, Kanagawa Prefecture, on Oct. 2, 2021. (Mainichi/Kentaro Ikushima)

TOKYO -- Contrary to some experts' warnings that the coronavirus sixth wave feared to hit Japan this winter could surpass the scale of the summer's fifth wave, which saw a sharp increase in COVID-19 patients and pressure on the medical system, artificial intelligence (AI) has recently produced interesting predictions that Tokyo might record 370 new cases daily at the sixth wave's peak, about the same as spring 2020's first wave.

    Daily new infections have stayed low in Japan of late, but can infections be brought under control without another outbreak?

    Japan's nationwide daily COVID-19 counts, which exceeded 25,000 at one point during the fifth wave, were down to just 77 on Nov. 24 -- a 99% decrease. On that day, Tokyo recorded five cases, the lowest this year.

    But experts are wary the sixth wave will be worse than the fifth. The central government is also assuming it will have double the infectivity of the delta-fueled fifth wave. Sixth wave preparations include creating a system by the end of November that can ensure 37,000 patients, 30% more than in the fifth wave, can be hospitalized.

    Amid this, predictions by an AI developed by Professor Akimasa Hirata's team at Nagoya Institute of Technology are attracting attention. To make the estimate, the team made the AI memorize vaccine efficacy, past outbreaks' cycles, the schedule of major vacations in Japan and other factors.

    For Tokyo, the AI predicted that new daily infection cases would continue to be 50 or less for the rest of the year, with increases starting around the end of 2021 due to year-end parties and people returning to their hometowns. Even so, it estimated the peak would be 370 in mid-January 2022.

    "It is a prerequisite that we continue measures against infection, such as wearing masks, but vaccinations' impact is significant. Not just in Tokyo but also on a nationwide scale, the sixth wave this winter will be suppressed to one-fifth to one-tenth of the fifth wave," Hirata said.

    Professor Akimasa Hirata of Nagoya Institute of Technology (Photo courtesy of Akimasa Hirata)

    Third round vaccinations beginning in December are considered key to controlling infections. Without booster shots, the AI predicts that a decline in vaccine effectiveness will mean April 2022 sees infections on a scale equivalent to the fifth wave.

    Hirata said, "If the third round of vaccination starts Dec. 1 as scheduled, we may be able to prevent infections spreading without reducing human activity too much. But it is important to keep taking countermeasures against infections. Drugs (to treat COVID-19) are also gradually available, so if we can get through this winter, we may be a step closer to ending the pandemic."

    In fact, the AI has successfully predicted the new cases' rapid decline since this summer's fifth wave, when daily counts in Tokyo exceeded 5,000. During the infections peak on Aug. 12, Shigeru Omi, head of the government's coronavirus countermeasures subcommittee, asked the public to "reduce movement by 50%" to control infections.

    But at the time, Hirata indicated that even without reducing movement, daily COVID-19 cases would decrease rapidly after Sept. 10, and that by around Oct. 6, Tokyo's new cases would be down to 210. In the end, Oct. 6 recorded 149 infections.

    Looking at the world, however, the pandemic can't be said to be ending. A World Health Organization report released Nov. 14 showed there were about 3.3 million new infections per week, up on the previous seven days. About 50,000 deaths a week were reported.

    In the Nov. 14 report, the U.S. had the most new weekly cases per country with 550,684, up 8% from the previous week. It was followed by Russia with 275,579 (about the same as the previous week), Germany with 254,436 (up 50% from the previous week), the U.K. with 252,905 (about the same as the previous week), and Turkey with 180,167 (down 9% from the previous week).

    Atsuo Hamada, a specially appointed professor at Tokyo Medical University and an infectious diseases expert, said, "Countries experiencing increases may be doing so due to winter's arrival. It is believed the coronavirus spreads more in winter."

    Although the AI predicts a relatively small outbreak, Hamada stressed: "We should be prepared for a sixth wave in Japan, too."

    (Japanese original by Naomi Hayashi, Lifestyle and Medical News Department)

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