TOKYO—An enduring mystery of the Covid-19 pandemic is why East Asian countries across the board have experienced far fewer cases and deaths than the U.S. and Europe.
Some doctors and scientists are beginning to take a closer look at theories that some people in East Asia and Southeast Asia have had different exposure to previous coronaviruses resembling the SARS-CoV-2 virus sweeping the globe. Such exposure could have protected them from getting sick from Covid-19 or lessened the severity of the disease.
Others doubt that the immune systems of people in the region differ from people in the rest of the world in any systematic way. They suspect cultural factors and, in some countries, government policies such as tightly enforced quarantines are playing the main role.
Whatever the case, doctors agree that some explanation is needed for why Japan, South Korea, China, Vietnam, Taiwan, Malaysia and Singapore all have experienced at most a few thousand new SARS-CoV-2 infections a day, even during the current surge. That compares with tens of thousands of daily cases in many European nations and more than 150,000 new cases on many days in the U.S.
Yasuhiro Suzuki has pondered the question as the highest-ranking doctor in the Japanese Ministry of Health, Labor and Welfare’s medical corps until his retirement in August.