Two individuals in Hong Kong known to be infected with the new Omicron variant of Covid-19 have reportedly been discovered to be carrying a high viral load, prompting concern about how effective current vaccines will be against the variant.
The pair took PCR tests that showed Ct values of 18 and 19.
"The viral load of these two with #B11529 in Hong Kong hotels were VERY high. PCR Ct values of 18 and 19!!! That's insanely high considering they were negative on recent PCR tests," epidemiologist Eric Feigl-Ding said in a tweet. "Looks like vaccine evasion could be real with this variant," he added.
Governments around the world have moved quickly to restrict travel in order to slow the spread of the potentially more dangerous coronavirus variant B.1.1.529.
The variant, named Omicron, has so far been detected in South Africa, Botswana, Hong Kong, Israel and Belgium.
The World Health Organization and the European Centre for Disease Prevention and Control have both expressed serious concern at the variant's large number of mutations, which may significantly reduce the effectiveness of vaccines and increase the risk of reinfection.
The Hong Kong authorities say the variant was brought to the territory by the traveller from South Africa who has been staying in a quarantine hotel since arriving on 11 November.
Another infected person
However, the virus was only detected after the man took a second PCR test on 13 November.
The authorities believe that the 36-year-old South African could have infected a 62-year-old in the room opposite his own despite both being in strict isolation.
The latter also tested positive for the new virus variant in his fourth PCR test on 18 November.
The South African may have transmitted the variant when he opened his door to receive his meals, Hong Kong officials have said.
Both patients are reportedly fully vaccinated.