Why US, Europe were hit harder by Covid-19? Scientists look at regional disparities, immune system

Researchers examined differences in genetics and immune system responses, separate virus strains and regional contrasts in obesity levels and general health.

A new study has said that regional differences play a major role in mutating the strains of coronavirus and making it innately contagious as well as lethal in one part of the world than in another.

The study has been conducted by Japanese researchers and reported by various Japanese media outlets.

Researchers examined differences in genetics and immune system responses, separate virus strains and regional contrasts in obesity levels and general health, apart from the quick reaction time to the crisis in many countries of Asia.

Giving example of China, where the outbreak started in December last year, the scientists said that the country reported less than 5,000 deaths since the outbreak began, 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.

They then said that there were 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.

“That means we need to take into consideration regional differences first, before analysing what policies and other factors are affecting the spread of infection in any given country,” said Akihiro Hisaka of China University’s Graduate School of Pharmaceutical Sciences.

Reacting to the research, Tatsuhiko Kodama of the University of Tokyo told Japanese media that preliminary studies show that Japanese people’s immune systems tend to react to the novel coronavirus “as though they had previous exposure”. He also noted that there are centuries of history of coronaviruses emerging from East Asia.

Several studies had earlier suggested that heat and humidity can slow the spread of the virus. But such findings were squashed after equatorial countries like Ecuador and Brazil saw severe growth in infected cases and deaths linked to Covid-19.