Genetic ‘X-factor’ may be behind Japan’s Covid-19 success

Daily Covid cases in the country reached more than 23,000 on August 26 but have since fallen sharply to around 100 a day, with numbers remaining steady even as it heads into winter.

Scientists have struggled to explain the dramatic turnaround with some pointing to the influence of some ‘X-factor’. One theory suggested the virus was driven to a “natural extinction” after several mutations led to it being unable to make copies of itself.

However, Japanese researchers from the Riken Institute in Tokyo have now found a possible genetic advantage that may explain the country’s success, and published their findings in the British journal Communications Biology last week.

The researchers found ethnic Japanese people are more likely to have a specific genetic feature related to white blood cells that could be helping the body to fight Covid-19.

“It could be considered an ‘X-factor’,” Riken immunotherapy laboratory team leader Professor Shin-ichiro Fujii told Nikkei Asia.

The protein located on the surface of white blood cells called HLA-A24, is common among some Asian groups, and is found in about 60 per cent of ethnic Japanese people, but is only present around 10-20 per cent of European and American populations.

HLA-A24 helps to activate the body’s killer T cells and researchers believe that the protein helps T-cells to remember past infections caused by seasonal coronaviruses and to potentially respond when exposed to Covid-19.