British, South African, Brazilian, Nigerian, Ugandan, Californian? The coronavirus is constantly mutating and new variants are proliferating in every corner of the globe. Known colloquially by the name of the country in which they arise, a hospital in Tokyo has now detected a new version of SARS-CoV-2 that joins all the previous ones and is worrying because of the possible effects on the population: the Japanese one.

This variant presents the E484K mutation, also known as ERIK and shared by the South African and Brazilian version of the coronavirus. This is a modification in SARS-CoV-2 that significantly reduces the effectiveness of vaccines, because it reduces the neutralizing capacity of some of the antibodies produced by stimulating the immune response that block the entry of the virus into cells. However, there are also concerns about its potential impact on the transmissibility of the disease.

This discovery comes during a new spike in infections that has particularly affected the city of Osaka and the prefectures of Hyogo and Miyagi and just a few months before the start of the Olympic Games in Tokyo, postponed last year because of the pandemic.

This new variant was detected by the Tokyo Medical and Dental University Hospital, which found that about 70% of patients tested in March for COVID-19 had been infected with it. The center sequenced the 14 positive individuals and found that 10 had been infected with this mutated virus.

In addition, in January and February, 12 of the 36 COVID-19-infected patients carried the mutation, and none of them had recently traveled abroad or been in contact with people who had, according to the hospital report.

Currently, there are two main branches with this E484K mutation: South African and Brazilian, plus a few isolated events. The E484K mutation that characterizes this Japanese variant affects the ability to neutralize virus entry into cells. This characteristic can reduce the effectiveness of vaccines and of the immunity generated by previous infections.

This mutation greatly affects the neutralizing capacity of some of the antibodies produced by stimulating the immune response that block the entry of the virus into our cells. When we have been infected before with other different variants, some antibodies don’t work. However, that does not mean that we stop having immunity. It is able to reduce the effectiveness, but it does not eliminate it.

In this sense, he adds that, in addition to neutralizing antibodies, there are also other forms of immunity to protect against the coronavirus, such as T cells.

Just as the N501Y mutation – present in the British version of the virus – does induce an increase in the capacity for contagion, it is not clear that the same occurs with the E484K. Does it lead to greater transmissibility? It could affect, but it is not fully demonstrated. However, it can be inferred from the success in prevalence, because they have displaced other variants.

As for mortality, these new variants have not been shown to be more virulent. However, he stresses that, if transmissibility is greater, the number of patients and the saturation of hospitals will increase, which may lead to poorer care and an increase in deaths.

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