My pet theory is that the new strains from Britain and India are more heat resistant, taking away their geographical advantage. Even states like Malaysia and Indonesia which didn’t implement strict lockdowns did well last year.
My pet theory, highly speculative and partially based on some studies.
1. Coronavirus was first encountered by Mankind as early as 25,000 years ago.
2. Areas where the bats that are infected with bat coronavirus are in Africa and Southeast Asia, especially around the mountain ranges in the south of China bordering Myanmar, Thailand and Vietnam.
3. African, South Asian and Southeast Asian developed some genetic immunity against coronavirus in general from thousands of years of microevolution.
3.a. Natural immunity continued to be reinforced with successive epidemics of not just coronaviruses but of other viruses in general.
3.b. Do you remember when Europeans first began to invade into Southern Asia, as in the Greek invasion of India led by Alexander the Great? Yes, the Greeks got sick.
4. The particular coronavirus, the prototype, begins to migrate out of the African, South Asian and Southeast Asian population thanks to globalization.
5. Comes upon northern populations that do not have natural genetic immunity against coronavirus. This is where it begins evolving and spreading. Northern populations I would refer to as northern Asian and European.
6. Evolution reached a point in Wuhan, where the virus has a good population to feed on non immune northern Asian as in north of the Yangtze origin, lacking enough of the south of the Yangtze tribal native genetics that confer natural immunity.
6. a. Countries that have a large part of Southeast Asian or South of Yangtze ethnic genetics include Japan, Taiwan, South Korea, Vietnam, Thailand, India, Myanmar, Malaysia, Indonesia, Philippines, etc,. This is due to the historic migrations and immigration such as that of Austranesian, Austra-Asiatic, Austro-Tai, Bai-Yue, and Mon-Khmer. Covid infections are relatively low per capita in 2020, due to a some part, natural immunity reinforced by lock downs and masking.
6. b. If it were not for the lock downs, northern Chinese populations would have been imperiled, even if Southern Chinese populations are more resistant to the virus.
7. Separately, evolution reached a point in Europe, where the proto-SARS-COV2 finds massive population of the non immune. The virus thrives and evolved there, finding little to no resistance.
7.a. Due to natural immunity in Africa, the virus does not gain much of a foothold in that continent.
8. While the virus is evolution stable, as in it does not mutate as much as other viruses. having a large population to infect on with no natural immunity means the virus is able to spread and replicate quickly, which speeds up its evolutionary clock, rapidly creating mutants.
9. As it turns out that mutants that evolved have reached a point that are able to challenge the naturally and genetically acquired immunity conferred upon African, South Asian and South East Asian people.
9.a. Led to the South African variant, now spreading in Africa. Led to the UK, Brazilian and Indian variants that appear to be more successful in infecting southern people.
9.b. Areas and countries that had a low covid infection per capita in 2020, such as those in Africa, South Asia, Northeast and South East Asia, are now having a surge thanks to the mutations that are now are able to successfully challenge the natural immunity of these ethnic groups.
10. This completes the evolutionary boomerang.