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Severe COVID-19 cases increase among middle-aged amid 5th wave in Tokyo

Medical staff are seen attending to a patient in a ward for those with severe symptoms at Juntendo University Hospital in Tokyo's Bunkyo Ward on July 23, 2021. (Mainichi/Tatsuya Fujii)

TOKYO -- The number of serious COVID-19 cases among those in their 40s to 50s has been on the rise amid the fifth coronavirus wave in Japan's capital, outstripping the figure for adults aged in their 70s or older.

    While there has been a decrease in elderly individuals who develop severe symptoms compared to the third coronavirus wave at the beginning of 2021, as well as the fourth wave during this spring, figures for individuals in their 40s to 50s have increased. In the medical field, moderate symptoms have apparently also been prevalent among patients in their 20s to 30s. What has been happening among the younger generations, who were thought to have a lower tendency to develop severe symptoms?

    "Compared to the third wave, there has been a significant increase in the hospitalization of younger patients," said Japanese Red Cross Omori Hospital Director Hirofumi Nakase regarding the latest state of infections.

    This hospital in Tokyo's Ota Ward has been accepting many patients who live in elderly care facilities where COVID-19 infection clusters have occurred. However, all 12 COVID-19 patients who were hospitalized at the institution as of July 21 were aged 65 or younger, while as many as eight patients were in their 50s or below. All eight patients had temporarily developed moderate or worse symptoms requiring oxygen administration measures.

    It is also evident from Tokyo Metropolitan Government statistics that younger adults have been developing more serious cases amid the fifth wave. According to metropolitan government figures, a total of 47 people aged in their 40s to 50s had severe coronavirus symptoms on July 28. This figure exceeded the greatest numbers reported for this group during the third and fourth waves -- 28 people on Jan. 12 and 25 people on May 11.

    As for the group of senior citizens aged in their 70s or older, the number of individuals with severe symptoms reached 88 on Jan. 27 during the third wave, and 35 on June 2 during the fourth wave, but the figure was around 20 people during the latest fifth wave. It is believed that the striking increase in severe symptoms among those in their 40s to 50s out of all age groups is due to this particular age group having greater risks of symptoms worsening due to higher smoking rates, obesity and diabetes.

    Furthermore, the spread of the Delta variant of the virus, which is said to be more transmissible than the conventional strain and also more likely to lead to serious COVID-19 cases, is also one factor behind the surge in younger adults' development of severe symptoms. According to estimates by the National Institute of Infectious Diseases, viruses with a L452R mutation seen in the Delta variant accounted for 61% of coronavirus strains in the greater Tokyo area as of July 19. At the beginning of August, viruses with this mutation accounted for 80%, and it is estimated that almost all coronavirus cases will be replaced by those with the L452R mutation by the end of this month.

    While many elderly individuals have received their second vaccine shot, vaccinations for younger adults have not been moving forward adequately, and this has influenced the increase in serious cases among the young and middle-aged. Documents from the prime minister's office showed that 73% of adults aged 65 or older had completed their second round of vaccinations by July 29, while only 28% of people in all age groups had been fully vaccinated.

    In the United Kingdom, where the Delta variant became dominant at an earlier stage than Japan, many recent COVID-19 cases were those among the young generation. According to reporting by the BBC on June 11, infections with the Delta variant accounted for 90% of COVID-19 cases, and about two-thirds of people infected with the Delta variant reportedly had not received vaccines.

    Tomohiro Ota, head of the respiratory medicine department at the Japanese Red Cross Omori Hospital, pointed out that there may be a higher tendency for infections spreading within the home, due to the highly transmissible nature of the Delta variant. He said, "Previously, around one other family member was infected at most in infections that spread at home. Now, it is not unusual for all family members to get infected." Although the young generation was said to be unlikely to develop severe symptoms, he said that there are recently many patients with intense symptoms, including fevers that will not get better even after using antipyretics.

    The number of COVID-19 patients has been continuously increasing in Tokyo. Omori Hospital Director Nakase expressed a sense of crisis, saying, "At this rate, it is possible that there will be patients who are not able to be hospitalized even if it's necessary." Meanwhile, there has been a decrease in the hospitalization of the elderly, for which vaccinations have moved forward. Dr. Ota said, "If vaccinations are pushed forward across Japan, infections will likely be able to be controlled to a certain extent," and stressed the importance of vaccines.

    (Japanese original by Yuki Ogawa, Lifestyle and Medical News Department)

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