Parts of Asia reacted quickly to the threat and largely started social distancing earlier on
The spreading coronavirus has health officials from the US to Europe searching for answers. To find them, they could look to the experience of Asia, which has been battling the deadly pathogen since January — with some success.
In a little over four months, the highly contagious disease has traveled from its epicenter in Wuhan, China, to at least 213 countries, sickened over 6,099,619 people and killed more than 369,012. Governments everywhere are struggling to curb outbreaks, locking down their borders and shutting down large parts of their economies.
But, it is one of the many mysteries of the coronavirus pandemic: Why has the death toll from Covid-19 apparently been lower in Asia than in Western Europe and North America?
Even allowing for different testing policies and counting methods, and questions over full disclosure of cases, stark differences in mortality across the world have caught the attention of researchers trying to crack the coronavirus code.
Parts of Asia reacted quickly to the threat and largely started social distancing earlier on. But researchers are also examining other factors, including differences in genetics and immune system responses, separate virus strains and regional contrasts in obesity levels and general health.
A major American daily newspaper, The Washington Post, tried to analyze the issue.
What are the numbers?
China, where the virus emerged late last year in Wuhan, has recorded fewer than 5,000 deaths, which translates to three deaths per million inhabitants. Japan has around seven per million, Pakistan six, South Korea and Indonesia five, India three and Thailand fewer than one per million. Vietnam, Cambodia and Mongolia say they have recorded zero covid-19-related deaths.
Compare that with about 100 deaths per million in Germany, about 180 in Canada, nearly 300 in the United States and more than 500 in Britain, Italy and Spain.
Scientists at Japan’s Chiba University plotted the trajectory of the virus across the world and said they noticed stark regional disparities.
“That means we need to take into consideration regional differences first, before analyzing what policies and other factors are affecting the spread of infection in any given country,” said Akihiro Hisaka of the university’s Graduate School of Pharmaceutical Sciences.
The conventional wisdom
The baseline assumption, at the moment, is that the virus — officially SARS-CoV-2 — mutates the way all viruses do and is just as innately contagious and lethal in one part of the world as in another.
Part of the reason for the high number of deaths in the United States and Western Europe may lie in an initial reluctance to react to an epidemic that seemed distant and unthreatening. In Asia, meanwhile, previous experience with the SARS and MERS epidemics enabled much faster responses to the new threat.
But in Japan and India, two very different countries, the relatively low death toll has baffled many scientists. Similar mysteries have emerged from Pakistan to the Philippines.
Weather and culture a reason?
Hot and humid weather could be a factor in places such as Cambodia, Vietnam and Singapore.
Several studies have suggested that heat and humidity can slow, although not stop, the spread of the virus, just as is seen with influenza and with coronaviruses that cause common colds.
But some equatorial countries, including Ecuador and Brazil, have seen many cases and deaths linked to Covid-19.
Demographics also play a role in regional disparities. Africa’s generally younger population may have been more resistant than northern Italy’s older communities, for example.
What about different strains?
Research by a team at Cambridge University showed how the virus mutated as it left East Asia and travelled to Europe, noting the possibility that the initial strain may have been “immunologically or environmentally adapted to a large section of the East Asian population” and needed to mutate to overcome resistance outside that region.
Genes and immune systems
Nobel laureate Tasuku Honjo, a Japanese physician-scientist and immunologist, said people with Asian and European ancestry have enormous differences in the human leukocyte antigen (HLA) haplotype, genes that control the immune system’s response to a virus.
That might help explain lower Asian death rates, he said, but is unlikely to be the only reason.