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It is striking that East Asian, South East Asian and South Pacific Populations appear relatively unscathed by the second and subsequent waves of the SARS-CoV-2 pandemic compared to the rest of the world. This is more so with the more infectious G614 mutation of COVID-19. Adherence to social distancing measures and face protection do not explain the almost 30-fold difference in infection incidence between Asian and European/American populations. The populations in the Indian Subcontinent are an exception, as infections rates were elevated compared to other Asian countries.
Differences in immune responses between European and African populations have been alluded to because of archaic introgression of immune-related Neanderthal genes in the European genome. As opposed to the European genome, the Asian genome has a higher introgression of the Neanderthal’s sister species’ genes, the Denisovan genes, which are more commonly found in East and South East Asia and the South Pacific populations. Contrastingly the Denisonvan genes are scantily found in the populations of the Indian Subcontinent.
Lockdown in China and bordering nations, led to significant reductions in atmospheric pollution, which itself significantly attenuates pulmonary immunity. Following lockdown in January the G614 variant emerged in China. With improved immunity following lockdown, the Denisovan immunity-related gene may have been allowed to be expressed more effectively, protecting Asian populations against the more infectious G614 variant of SARS-CoV-2 during the subsequent waves of the pandemic.