ASOURCE Navi

Influenza cases begin in earnest after November every year, but this season there were only a few people who contracted the flu last season, so herd immunity in society as a whole has not been formed, and there are concerns about a major epidemic. It has been. In addition, the sixth wave of the new corona is expected, and there is a possibility of a simultaneous epidemic with influenza, and it has been pointed out that there is a risk of medical collapse.

The estimated number of influenza patients last season was about 14,000, a sharp drop from the 7.29 million the year before last. The reason for this is that more people are wary of the new coronavirus and take measures such as wearing masks, washing hands, gargling, maintaining social distance, and avoiding the three Cs. In addition, border measures such as immigration restrictions are believed to have been effective. In addition, it has been pointed out that the epidemic of the new coronavirus may have caused the phenomenon of ``viral interference,'' which hinders the spread of other types of viruses.

This season (2021-2022 season), the number of people who got the flu last season was small, so herd immunity in society as a whole is low, and there are concerns about a large-scale influenza epidemic. Herd immunity means that once a certain number of a population acquires immunity to an infectious disease, even if an infected patient appears in the population, the epidemic can be stopped and the spread of the infectious disease can be prevented. It has been pointed out that a serious and long-term epidemic may occur when herd immunity declines, as many people do not have immunity to influenza. In addition, as the novel coronavirus epidemic subsides, immigration restrictions will be eased, raising concerns about an increase in the movement of people across borders. So far, no epidemics have been observed in the southern hemisphere, such as Australia, but in countries closely related to Japan, such as Bangladesh, India, Pakistan, and Nepal, influenza is currently prevalent, with A(H1N1)pdm09, A Hong Kong type (H3N2), B/Victoria virus, etc. have been detected. If influenza is introduced from these countries, there is a risk of causing a large-scale influenza epidemic.

If a large-scale influenza epidemic were to occur this winter, more than 12 million patients would be affected nationwide. Unprecedented confusion is expected. Taisuke Nakata, an associate professor at the University of Tokyo Graduate School of Economics, said that he will return to pre-corona social activities for three months from November 2020, and that the corona vaccination rate will reach 80% of the population by the end of the year. According to a simulation, it is estimated that the sixth wave will peak in Tokyo around mid-February 2022, and the number of new infections will exceed 10,000 per day. In addition, it is hypothesized that the increase and decrease in the number of new corona infections will occur in a two-month cycle, and if it bottoms out in October and starts to increase, it is speculated that it will peak again in December.

There have been reports of breakthrough infections, in which people can be infected even after completing their vaccination against the coronavirus, and if they have a fever or cough, the possibility of contracting the disease cannot be denied. In addition, since the initial symptoms of the new coronavirus and influenza are similar, it is difficult to distinguish between them in the clinical setting.

For this reason, the Japanese Association for Infectious Diseases is calling for active vaccination against influenza. The supply of vaccines this season is 26 million bottles (about 52 million people), which is about 20% less than last season. Influenza vaccines are said to be effective in preventing hospitalization due to aggravation of complications in the elderly, as well as being effective in preventing the onset of symptoms in young children. The British government is also calling on the public to get vaccinated, saying that this season's flu epidemic could be 1.5 times the size of an average year.