English abstract
Reasons underlying the sharp decline in COVID-19 cases in Japan as a geopolitical local advantage
TIME introduced the successful COVID-19 countermeasures achieved by Japan in an article titled “Japan’s Plummeting COVID-19 Cases Create Mysterious Success Story.”
With the COVID-19 pandemic in Japan coming to a near end, I have mentioned that the geopolitical aspects are significantly essential.
I consider two factors for these geopolitical aspects. The first is immunity acquired from the seasonal coronavirus. The second is the high activity of an enzyme called apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like (APOBEC). In several countries, infections are exploding despite the high rates of vaccination. As such, one can infer that vaccination is not the cause of the sharp decline in the positive cases of COVID-19 in Japan.
As demonstrated by the WHO diagram, large regional differences exist in terms of the damages caused by COVID-19. For example, damage to countries in Asia, such as China, and in the Middle East, has been relatively and clearly reduced. The majority of the Japanese have been exposed to the seasonal coronavirus since childhood. My assumption is that the seasonal coronavirus infection exerted a certain degree of immunity on the Japanese.
The other is about factors on the host side. Originally, mutation is difficult for coronavirus because it has a site called NSP14 that performs gene repair. Thus, it can only mutate approximately in 1/10 of influenza.
Apart from the immune system, several cells in the human body employ certain methods that kill viruses. An example is the APOBEC enzyme family found in human cells.
A team from the National Institute of Genetics in Japan and Niigata University reported that many people display strong APOBEC activity in Asia and Oceania, including Japan. The ancient coronavirus pandemic that coexisted with Chinese civets and camels in the Middle East may have been eliminated due to the high levels of APOBEC activity in humans.
The figure indicates the wave of infectious diseases in Japan, which may be common in countries where COVID-19 cases are declining. In other words, these countries have undergone a number of big waves of natural infections. Japan has overcome five big waves (in my opinion, they should have been six waves and next wave will be seventh). I assume that the reason for overcoming them is not merely self-restraint, the public’s sense of crisis, or the vaccination rate as put forward by experts. Consequently, experts are unable to explain the reason for the sharp decline in the number of positive cases.
The Japanese have repeatedly overcome waves of natural epidemics and controlled for damage using geopolitical advantages at the same time. For this reason, the number of positive cases of COVID-19 in Japan has sharply declined.
I further predict the future of SARS-CoV-2. If APOBEC is an enzyme activated by cytotoxicity, then the less virulent SARS-CoV-2 virus will be survived after being weeded out. Since ancient times, various coronaviruses have coexisted with repeated animal-human infections (ref. 7). Similar to the existing coronaviruses, SARS-CoV2 is expected to become one of the attenuated viruses that coexist with humans worldwide. We are only observing the new processes of the addition of new coronavirus.