In COVID-19 era, impact of restricted movement of people on the seasonal influenza pandemic

Although the intervention of the monitoring and pharmaceutical and non-pharmaceutical products is being carried out against the influenza virus for decades, the seasonal influenza virus continues to cause epidemics around the world at every year. However, in countries around the world, the number of people infected with the seasonal influenza virus during the COVID-19 era, 2019-2020 and 2020-2021 has decreased significantly. Masks, hand washing, and social distance, which are preventive measures against COVID-19 infection, are considered to be the cause of the significant decrease in the number of people infected with the seasonal influenza virus. However, even in South American countries where COVID-19 infection control measures are weak, the number of people infected with the seasonal influenza virus has decreased significantly. In other words, another factor other than the precaution against COVID-19 infection, has been strongly influenced to a significant reduction of the number of peoples with seasonal influenza virus infection.

According to medical and public health experts, the significant decrease in the number of people coming to each clinic for influenza testing may be the cause of the significant decrease in the number of people infected with seasonal influenza in 2019-2020. In addition, the significant decline in seasonal influenza infections in 2019-2020 is also due to the effectiveness of policies such as hand washing and social distance to prevent COVID-19 infection.

In addition, the number of people infected with seasonal influenza, which is feared to be a simultaneous epidemic with COVID-19, has been reported in Japan. The number of cases reported in the week to December 13, 2020 is 57 nationwide. Compared to the average number of people infected with seasonal influenza, the number of people infected with seasonal influenza in 2020-2021 continues to be significantly lower. According to a report by the National Institute of Infectious Diseases in Japan, the signs of the epidemic of seasonal influenza in Japan has not yet been recognized. The Japanese government is calling on the Japanese people to be aware of the upcoming seasonal influenza epidemic.

After the early end of the season of seasonal influenza in the Northern Hemisphere, there was no epidemic of 2020 seasonal influenza in the Southern Hemisphere. In the southern hemisphere, to July from April 2020, even though the number of cases worldwide COVID-19 has continued to increase, the number of cases of seasonal influenza infection was extremely small. Australia, Chile, in South Africa, in the examination more than 83,000 samples for seasonal influenza, the total seasonal positive for influenza was only of 51 people.

Some countries in South America do not have good policies as a precautionary measure against COVID-19. However, even in such countries, the number of people infected with seasonal influenza is extremely small. In other words, the absence of people infected with seasonal influenza is not solely due to wearing masks, washing hands, and social distance as a countermeasure against the COVID-19 pandemic.

Previous studies have revealed that humans are the vehicle for the new virus that causes emerging infections. In other words, it has been clarified that the flow and circulation of the new virus depends on the global movement of people. In other words, it is natural to think that the suppression of global movement of people will also suppress the global movement of seasonal influenza. Currently, with the spread of COVID-19 infection, various countries are tightening quarantine at the time of entry and exit (submission of health declarations, isolation measures) and are doing severely limits and immigration and VISA issuance. Each international airline is suspended or reduced in number according to national affairs.

The number of people infected with the 2020 seasonal influenza virus has also declined significantly in some South American countries, where good policies are not being implemented to prevent COVID-19. Perhaps, severe restriction of immigration in each country stops the global circulation of seasonal influenza virus. As a result, the number of people infected with the 2020-2021 seasonal influenza virus in each country is considered to have decreased significantly.

Author contributions
T.H. wrote the manuscript. I.K. carefully reviewed the manuscript and commented on aspects of clinical medicine, shared information on clinical medicine.

Disclosure of potential conflicts of interest
The authors declare no potential conflicts of interest.

Data availability and Consent to publish
This manuscript is an editorial and does not contain research data.
Therefore, there is no research data or information to be published or opened.

Acknowledgments
We thank all the medical staffs and co-medical staffs for providing and helping medical research at National Hospital Organization Kyoto Medical Center.

Science Published on January 2021. by Kyoto@Takuma H