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According to an official quoted by news agency PTI, he had not taken any COVID-19 vaccine since he had been at sea for months as a marine engineer. On 24th November, the passenger reported mild fever after landing in Mumbai and is being treated at the Covid Care Centre in Kalyan-Dombivali.
Twelve of the passenger's high-risk contacts and 23 low-risk contacts have been traced and all have tested negative for COVID-19. Additionally, 25 of his co-passengers from the Delhi-Mumbai flight have also tested negative. More contacts are currently being traced.
The Maharashtra government also said that the Omicron variant has not been detected in tests conducted on a 60-year-old man who had arrived from Zambia, who has instead been found to be positive for "a sub-lineage of Delta variant".
Earlier in the day, a man who returned from Zimbabwe was found infected with the Omicron variant of coronavirus in Gujarat's Jamnagar, the state health department said, in the third case of the strain in India.
The other two cases in India are of a 46-year-old fully vaccinated doctor from Bengaluru, who had no travel history and developed symptoms of fever and body ache, and a 66-year-old South African national who came to India with a negative COVID-19 report.
The country has stepped up testing and surveillance of all incoming international passengers, especially from at-risk nations since the Omicron variant was first detected in South Africa.
The World Health Organisation has said it could take weeks to determine whether Omicron is more transmissible and whether it causes more severe infections - as well as how effective current treatments and vaccines are against it.
But the new variant has already cast the world's recovery into doubt. More than two dozen nations including India have now detected cases of the variant.
The Health Ministry on Friday said it expects the Omicron variant to cause less severe disease, thanks to vaccinations and high prior exposure to the Delta variant that infected nearly 70 per cent of the population by July.
Nearly half of India's 944 million adults have been fully vaccinated. As many as 84 per cent have received at least one dose, with more than 125 million people eligible now as the government pushes more to get inoculated in the face of Omicron.