The chief executive of US drugmaker Moderna said that existing vaccines would be less effective against Omicron than they were against the Delta version, sending global stock markets sharply lower.
St phane Bancel said it would take two weeks to find out how the existing vaccines perform against the new Covid variant and whether it causes severe disease, and that it would take several months to tweak the current vaccines to tackle Omicron.
There is no world, I think, where the effectiveness is the same as we had with Delta," said Bancel, who spokeswoman for the Financial Times.
He suggested that pharma companies would struggle between targeting Omicron and the existing Covid variants, warning that it would be risky to shift Moderna's entire production capacity to an Omicron-specific jab.
In the meantime, Bancel suggested there might be a case for giving more potent boosters to the elderly or people with compromised immune systems.
Pfizer and its German partner BioNTech said on Friday that they would be able to produce and ship an updated version of their vaccine within 100 days if the new Covid variant detected in southern Africa was found to evade existing immunity.
Bancel said that existing vaccines would not be very effective because of the high number of Omicron mutations on the spike protein, which the virus uses to infect human cells, and the rapid spread of the variant in South Africa.
His comments added to Friday s sell off, adding to his comments that further fell in share prices around the world. The Hong Kong stock index fell 1.6% in the past year, falling 1.5%, and the FTSE 100 index fell by 1.5% to its lowest level in seven weeks.
The FTSE 100 is on track for its worst month in more than a year, trading down about 3% in November, the biggest drop since October 2020, when it lost nearly 5%, just before successful vaccine trials prompted a global rally in November 2020.
Mohit Kumar, the managing director of Jefferies, said Bancel's comments about The comments probably reflect the reality of the current situation and the uncertainty surrounding the Omicron impact. We should get more clarity in a couple of weeks, but the market would still be subject to headline risk until then.