In Japan, four people tested positive for the novel coronavirus in the airport, with the new mutant strain being detected through a detailed examination.

This was announced by Japan’s National Institute of Infectious Diseases.

According to Japan’s Ministry of Health, four passengers that arrived at Japan’s Haneda airport from Brazil on January 2 were later diagnosed with the virus. One male in his 40s, who was asymptomatic upon arrival, was hospitalized as his respiratory system worsened. A woman in her 30s had a headache and sore throat, and a teenage male had a fever. A teenage girl showed no symptoms.

The new variant has similarities to strains found in the U.K. and South Africa, the NIID said in a statement on Sunday. The information about the new variant is limited to its genetic make-up, and it’s difficult to immediately determine how infectious the strain is or the effectiveness of current vaccines against it, the institute said.

Possibly, another strain of the coronavirus infection may cause serious concern among health workers due to its higher contagiousness. Mutations N501Y and E484K were detected.

Brazil’s Health Ministry said it has been notified by Japanese authorities that the new variant has 12 mutations, one of which is also present in the variants found in the U.K. and South Africa. “It implies a potential higher virus infectiousness,” it said.

A ministry official said studies were underway into the efficacy of vaccines against the new variant.

“At the moment, there is no proof showing the new variant found in those from Brazil is high in infectiousness,” Takaji Wakita, head of the National Institute of Infectious Diseases (NIID), told a health ministry briefing.

Brazil’s Health Ministry asked the Japanese government to provide information on the new variant of the novel coronavirus detected in the four travelers. The ministry asked for information such as the genetic sequence of the new strain. Brazil is experiencing a second wave of coronavirus infections, with a daily average of more than 50,000 people testing positive for the virus in January. In Brazil, the mutant strains of the British and South African types have been confirmed. Meanwhile, in Japan, the government declared a state of emergency for Tokyo and three neighboring prefectures last week after seeing a steep rise in coronavirus cases.