＜prologue＞
I started a blog called “The Baby Boomer Generation’s Miscellaneous Blog”（Dankai-sedai no garakutatyou:団塊世代の我楽多（がらくた）帳） in July 2018, about a year before I fully retired. More than six years have passed since then, and the number of articles has increased considerably.
So, in order to make them accessible to people who don’t understand Japanese, I decided to translate my past articles into English and publish them.
It may sound a bit exaggerated, but I would like to make this my life’s work.
It should be noted that haiku and waka （Japanese short fixed form poems） are quite difficult to translate into English, so some parts are written in Japanese.
If you are interested in haiku or waka and would like to know more, please read introductory or specialized books on haiku or waka written in English.
I also write many articles about the Japanese language. I would be happy if these inspire more people to want to learn Japanese.
my blog’s URL:団塊世代の我楽多（がらくた）帳 | 団塊世代が雑学や面白い話を発信しています
my X’s URL:団塊世代の我楽多帳（@historia49) on X
Since the beginning of July, the number of domestic PCR-positive infections of “novel coronavirus pneumonia” has been rapidly increasing daily not only in Tokyo but also in Osaka, Aichi, Fukuoka, Hyogo, and Kanagawa prefectures, causing growing anxiety among the public. Some have suggested that a second wave has already occurred or that we are in the midst of a second wave.
The virus has been widely covered on television news and information programs every day, with some governors, the Tokyo Medical Association, and opposition parties making repeated statements denouncing the government’s lack of action.
However, everyone is talking about the coronavirus and feeling fear, and the media seems to be single-mindedly focusing on the virus, fueling anxiety. Personally, I believe this phenomenon should be called a “coronavirus frenzy.”
Amid this social climate at the mercy of the virus, one person is attracting attention by proposing a “new hypothesis” regarding the coronavirus. His name is Yasushi Takahashi, a professor at the International University of Health and Welfare Graduate School.
In this article, I would like to introduce Professor Takahashi’s “new hypothesis” in an easy-to-understand manner.
1. What is Professor Takahashi’s “new hypothesis”?
(1) Three Hypotheses Regarding the Novel Coronavirus
Hypothesis 1: It is Less Toxic Than Influenza
Hypothesis 2: A Certain Number of Japanese People Are Already Infected and Unknowingly Recovering
Hypothesis 3: The Maximum Death toll in Japan Will be 3,800
According to Professor Yasushi Takahashi, the novel coronavirus has a strong “exposure potential” (ability to enter the human body). However, even if “infection” occurs, the virus’s “proliferation potential” and “infectiousness” are weaker than influenza, and its “toxicity” (ability to stimulate and destroy human cells) is weaker.
When the novel coronavirus infects and is expelled from cells, its toxicity and proliferation are weak. Therefore, the body initially considers it an enemy that can be dealt with by innate immunity, and approximately 98% of cases are dealt with by innate immunity, resulting in a complete recovery.
Because the virus is suppressed by “innate immunity,” the first line of defense composed of phagocytic cells such as macrophages that ingest foreign substances, “acquired immunity” is slow to activate, and antibodies are difficult to produce.
In contrast, influenza’s strong toxicity means that the second line of defense, “acquired immunity,” is activated early, making it easier to produce antibodies.
A very small percentage of COVID-19 viruses evade innate immune attacks, in which case adaptive immunity kicks in and eliminates the virus.
Furthermore, a small percentage of these viruses can trigger a “cytokine storm,” a “runaway immune system,” in some people, causing severe illness and even death. Elderly people, those with weakened physical strength, high blood pressure, and obesity are apparently at higher risk of a “cytokine storm.”
This is related to the issue of “herd immunity” that I wrote about in a previous article.
(2) Three factors why the rate of severe illness and death in Japanese people is lower than in Europe and the United States
There are three reasons why the severity and mortality rates of Japanese people are lower than those of Westerners.
Factor 1: Environmental
Elderly care facilities have strict systems in place to isolate high-risk elderly people from the virus, and each elderly person also voluntarily isolates themselves.
Factor 2: Innate Immunity
Japanese people have stronger innate immunity than Westerners for some reason (theories include the BCG theory).
Factor 3: Constitution
Japanese people are less likely to experience a “cytokine storm” than Westerners, and even if they do, they are less likely to develop blood clots and become severely ill.
(3) Basis for the Speculation that 30% of Japanese People Have Already Been “Exposed”
This is an assumption that “30% of Japanese people have already been infected with COVID-19 without knowing it and have recovered without even realizing it.”
This is the result of simulations using several “exposure rates” based on data on the number of severe cases and deaths. From this, they then predicted the number of severe cases and deaths if all Japanese people were exposed.
2. What is Professor Yasushi Takahashi’s “infection stage-specific model”?
Professor Takahashi Yasushi has proposed a “7-stage infection model” for COVID-19, as shown in the diagram above.
This model classifies the stages of COVID-19 infection into seven stages, from stage zero to stage six, and “visualizes” the probability and factors that lead to each stage.
In the seven-stage model, “natural immunity” is the key dividing point between mild and severe symptoms.
After conducting simulations, he has apparently reached the following conclusions.
1) At least 30% of the population has already been exposed to COVID-19, and up to 45% may have been exposed.
2) 98% of exposed people were asymptomatic or recovered with cold-like symptoms in Stage 1 or 2 (i.e., they were able to cope with the disease through “natural immunity”).
3) 2% of exposed people had their “adapted immunity” activated, meaning they progressed to Stage 3 or 4.
4) Furthermore, among those 2% exposed, a “cytokine storm” occurred, leading to severe disease (Stage 5). This figure was approximately 5 out of 100,000 people in their 20s, 3 out of 10,000 people in the 30-59 age group, 1 out of 1,000 people in the 60-69 age group, and 3 out of 1,000 people in the 70+ age group.
3. How do you view the spread of COVID-19 in urban areas?
In the diagram above, the “area surrounded by a light blue square” represents “people exposed to COVID-19.” Among them, the colored ones are “those who became infected.”
However, many of the “people shown in blue” have strong innate immunity, and most are asymptomatic or have mild symptoms that go unnoticed, shed very little virus, and do not become spreaders.
Meanwhile, “people shown in yellow” are “unaware spreaders” who temporarily shed virus but recover with innate immunity.
Although the incidence rate is low, there are also “people shown in orange” whose acquired immunity is activated when innate immunity cannot suppress the virus, causing severe cold-like symptoms and shed large amounts of virus, thereby transmitting it to others.
Furthermore, “people shown in red” develop obvious symptoms such as fever and cough, and when they test positive for COVID-19 they are hospitalized.
PCR testing is currently being rapidly increased, and the number of positive cases is on the rise. However, the “effective reproduction number” was said to have peaked in late March, even though the number of tests was low. Professor Takahashi Yasushi believes that “if we had conducted PCR tests at this time and at the same rate as we are now, we would have found tens to hundreds of times more positive cases than we are now.”
4. Is there any point in increasing PCR testing?
Professor Takahashi Yasushi points out that placing importance on the “number of PCR-positive cases” is questionable. Even if you have antibodies, you can still test positive on a PCR test, and even if you test negative, you could be exposed and test positive the next day.
A “negative” PCR result means that you have not been infected with COVID-19 for about a week prior to the test. It does not rule out the possibility of infection two weeks prior or immediately after the test. In that sense, a “negative certificate” is virtually meaningless.
Focusing on “infected individuals,” rapidly expanding testing of asymptomatic individuals, and hospitalizing or isolating those who test positive places an excessive burden on medical professionals such as doctors and nurses, wasting medical supplies, and risking overwhelmed critical patients.
Furthermore, restricting the social and economic activities of asymptomatic individuals who are hospitalized or isolated results in significant losses for society as a whole.
I’m a complete novice when it comes to medicine, but with regards to COVID-19, I believe that “as with any other illness, anyone with symptoms should see a doctor and undergo PCR testing.” However, I think it’s time to reconsider the current approach of tracking clusters and having close contacts undergo PCR testing widely.
I think this is the issue of “triage” that I wrote about in a previous article.
5. The number of “positive test results” is increasing rapidly around the world, but the increase in the “death toll” is not
Looking at the world as a whole, just as in Japan, the number of positive tests is increasing rapidly due to an expansion in testing, but the increase in the number of deaths is not as rapid.
Rather, there is concern that the stagnation of the economy will lead to a sharp increase in suicides.
In addition, many people are postponing health checkups out of fear of contracting COVID-19 (I am one of them), which is feared to delay the detection of early-stage cancers that would normally be detected, and result in lives that could be saved being missed.
Furthermore, research has shown that weight gain due to “staying at home” increases the amount of ACE2 adaptor on cell surfaces, increasing the likelihood of infection and severe illness.
It seems that an increasing number of elderly people are unable to attend day care centers and day services, which is leading to worsening dementia and weakening of the legs and back.
The validity of this “new hypothesis” will be “verified” once the coronavirus pandemic has subsided, but taking all of the above into consideration, I believe that Professor Takahashi’s “new hypothesis” is worth listening to.
I would like to ask the Japanese government and local government leaders to review their coronavirus countermeasures, taking these into consideration, rather than relying solely on expanding PCR testing, refraining from activities, and requesting business closures.
While thorough coronavirus infection prevention measures are important, excessive self-restraint is a problem, and I believe it is essential to strike an appropriate balance with economic activity.