Thailand’s new Kraken, Orthrus strains evade immunity, virologist warns
The Kraken and Orthrus subvariants of Omicron recently found in Thailand can evade people’s existing immunity to Covid-19, Chulalongkorn University's top virologist warned on Wednesday.
Writing on Facebook, Yong Poovorawan said the two new strains showed Covid-19’s ability to mutate over time to escape human immunity. Hence, people can be infected with the virus at any time, he added.
He said Kraken, or Omicron XBB.1.5, is spreading rapidly from the US and Europe and could soon become the dominant variant. The strain is named after a legendary giant octopus said to destroy ships and kill sailors.
Yong said that this dangerous new Covid-19 subvariant should be monitored closely.
Orthrus, known scientifically as CH.1.1 and named after the two-headed dog in a Greek myth, is spreading in the US but has caused fewer infections than Kraken, he added.
The dominant strain in Thailand is still Omicron BA.2.75, which accounted for 88% of infections last month, said Yong, citing a study by Chulalongkorn University’s Centre of Excellence in Clinical Virology, which he heads.
However, one case of Kraken and four cases of Orthrus have been discovered in Thailand, he added.
"Even though the severity has not increased, these variants are dangerous as they can escape immunity," he said.