Tokyo Shimbun WEB: Declining Immunity and Emergence of New Mutant Strains Blamed for First Increase in COVID-19 Cases in Tokyo in 11 Weeks

The number of new coronavirus cases in Tokyo has increased for the first time in 11 weeks. In the week leading up to the 29th, the average number of individuals affected was 812 – a 1.4 times increase from the previous week. According to experts, this rise is due to the spread of new mutant strains, numerous year-end events, and a weakening immune system. It is “extremely difficult” to predict whether this number will continue to increase. Dr. Takao Omagari of the National Center for Global Health and Medicine spoke candidly to the press, stating that “It’s a little surprising how this number jumps up.” Some experts believe that the easing of mask-wearing rules may be a contributing factor. A recent survey conducted by the Tokyo Infectious Disease Control Center revealed that one in four individuals with a history of being infected with the new coronavirus suffered after-effects for two months or more. Symptoms included fatigue, burnout, coughs, and fever. The metropolitan government has set aside 30 million yen in its supplementary budget to deal with after-effects.

The number of new coronavirus infections in Tokyo increased for the first time in 11 weeks. According to the metropolitan monitoring meeting on the 30th, the average number of people for the week through the 29th was 812, 1.4 times the number from the previous week. As for the factors, experts cited the spread of new mutant strains, the holding of numerous events at the end of the fiscal year, and the weakening of the immune system of society as a whole. It is said that it is “extremely difficult” to predict whether the number will continue to increase in the future. (Chisato Miyake)

A monitoring meeting held by the Tokyo metropolitan government discussing the increase in the number of new coronavirus infections (provided by the metropolitan government on the 30th)

“It’s a little surprising how this number jumps up.” After the conference, Dr. Takao Omagari of the National Center for Global Health and Medicine spoke candidly to the press.

In the past eight days, the number of infected people exceeded the number of infected people on the same day of the previous week, and on the 28th and 29th, the number exceeded 1,000. More than 1,000 people have been since March 1st.

In the past, the chances of contact increased during welcome and farewell parties and cherry blossom viewing, and the infection spread. Furthermore, three months have passed since the most recent peak at the end of December, and the immunity of those who have been infected and those who have been vaccinated is declining.

Omagari said, “It is thought that the effective immunity of society as a whole is declining, so if things go in the wrong direction, the number of positive people could rise.” I don’t know,’ he says.

The current concern is the new mutant strain “XBB.1.5”. According to the genome (all genetic information) analysis results in early March, BA.5, which has long been the mainstay of patients in Tokyo since July last year, has surpassed for the first time to account for one-fourth. Mitsuo Kaku, head of the Tokyo Infectious Disease Control Center, warned, “It has 1.43 times higher infectivity than BA.5, and it also has a strong ability to escape immunity. It’s not a strain that easily causes serious illness, but we’ll keep a close eye on trends.” I let

Is it related to the easing of mask-wearing rules in the middle of this month that the number turned to increase at this timing? Mr. Omagari said, “There are quite a few people in Japan who have worn them even after the easing. I don’t think there will be much of an impact.” He again called for basic infection control measures such as wearing appropriate masks according to the situation, avoiding the three Cs, and regularly ventilating.

◆ 1 in 4 people have aftereffects of 2 months or more

At the metropolitan government’s monitoring meeting on the 30th, the results of a questionnaire were released showing that one in four people in Tokyo who had a history of being infected with the new coronavirus suffered aftereffects for two months or more.

In late February, 10,429 Tokyo residents responded to an online survey conducted by the Tokyo Infectious Disease Control Center. Of those, 19.6% said they had been infected with the new coronavirus, and 25.8% of those who said they had symptoms suggestive of aftereffects for more than two months accounted for more than 500 people. Of these, 85% said that they had difficulty in their daily lives, and 27.5% said they missed work or school for a week or more.

Symptoms are fatigue,burnoutKentai51.6% said “feeling”, 35.1% said “cough”, and 19.9% ​​each said “fever/slight fever” and “sputum production.”

The metropolitan government appropriated 30 million yen in the supplementary budget for the new fiscal year as a cost to deal with aftereffects. Expand the number of medical institutions that can examine aftereffects and create leaflets for companies to deepen understanding of aftereffects.





The increase in new coronavirus infections in Tokyo is an alarming development, particularly after 11 weeks of steady decline. Experts are citing the spread of new mutant strains, the holding of numerous events at the end of the fiscal year, and the weakening of the immune system of society as a whole as possible factors. It is difficult to predict whether the number will continue to increase in the future, and caution is being advised. Furthermore, the aftereffects of the virus are a growing concern, with one in four people in Tokyo suffering for two months or more. The metropolitan government is taking steps to deal with aftereffects and spread awareness about them. It is important to remain vigilant and continue following basic infection control measures such as wearing masks, avoiding the three Cs, and regularly ventilating to stay safe.

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