A new COVID-19 strain was found at an immigration centre in Tokyo, Japan. The variant has the E484K mutation, which was first identified in the South African SARS-CoV-2 variant.

Japan is currently in its third wave of infection in the pandemic and has identified the new variant in 91 cases in the Kanto area of eastern Japan. The chief cabinet secretary, Katsunobu Kato, confirmed two cases were flagged at airports.

At the time of publishing, Japan has a COVID-19 caseload of over 400 000, along with 7 194 fatalities.

New COVID-19 variant in Japan: What we know

Cases identified at airports in Japan

Kato confirmed that the government is increasing surveillance against new strains, and explained that the new strain “may be more contagious” than other “conventional strains”.

“If it continues to spread domestically, it could lead to a rapid rise in cases”.

Chief cabinet secretary, Katsunobu Kato

The new strain may have originated from elsewhere as the new cases flagged in Japan are different from other variants found sporadically in other parts of the country.

According to the National Institute of Infectious Diseases, the new strain has the E484K mutation on the spike protein of the virus that has been found in other variants.

New COVID-19 variant: What is the E484K mutation?

According to the BMJ, a weekly peer-reviewed medical trade journal published by the British Medical Association, the E484K mutation “is not a new variant in itself; it’s a mutation which occurs in different variants”.

“[It] has already been found in the South African (B.1.351) and Brazilian (B.1.1.28) variants. The mutation is in the spike protein and appears to have an impact on the body’s immune response and, possibly, vaccine efficacy”.

The Public Health England (PHE) on 1 February 2021 announced that the COVID19 Genomics (COG-UK) consortium “had identified this same E484K mutation in 11 samples carrying the UK variant B.1.1.7 after analysing 214 159 sequences”.

‘An escape mutation’

E484K, also known as “an escape mutation”, helps the virus slip past the body’s immune defences and increases the amount of serum antibody needed to prevent infection of cells.

Dr Ravindra Gupta at the University of Cambridge says the B.1.1.7 variant is more transmissible as it spreads faster and is better at evading immunity. The risk of reinfection is also higher.

According to Lawrence Young, a virologist and professor of molecular oncology at Warwick University:

“This is likely to be, in part, because the E484K mutation may weaken the immune response and also impact the longevity of the neutralising antibody response. So B.1.1.7 variants carrying the E484K mutation may be more efficient at reinfection”.

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Presh JM Reporter

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