No one knows how effective the vaccines will be in preventing people catching the newly discovered and rapidly spreading omicron variant of COVID-19 or how well they will protect against serious disease.
Lab trials are underway to determine the vaccine’s efficacy against Omicron, with results expected within weeks.
Meanwhile the delta version remains the dominant one and experts, governments and vaccine makers are urging people to take advantage of booster jabs where they are available.
The vaccine has been proven to protect against transmission as compared to Delta, Alpha, Beta and Gamma COVID variants.
But the jabs have been highly effective in preventing serious disease from the delta, reducing the risk of excessive hospital resources.
With Delta still dominated in Europe, some countries are trying to accelerate their third jab campaigns.
UK Prime Minister Boris Johnson has set a target of giving boosters to all adults by the end of January and reducing the waiting period between second and third jabs to six to three months.
In the US, Pfizer is seeking authorization for its jab to be given as a booster to 16- and 17-year-olds.
“It would be a grave mistake to slow down now,” said Alain Fischer, who coordinates France’s pandemic vaccine strategy.
“Our message is: don’t panic, the plan remains the same: expedite the administration of the third booster shot,” Ugur Sahin, co-founder of BioNTech, said on Tuesday.
But Moderna chief Stefan Bansel told the Financial Times this week that he expected “a material drop” in the shots’ effectiveness compared to the new version.
Laboratory tests are underway to measure Omicron’s sensitivity to vaccines in use today, a process that will yield results in two to three weeks.
Pfizer, Johnson & Johnson and Moderna each say they have begun work on a new version of their vaccine, specifically targeting Omicron — in case existing jabs don’t work against it.
When Delta arrived on the scene, Pfizer developed a jab specifically for the variant but never rolled it out.
“The labs ended up relying on the fact that their jaws are protected from severe COVID – but it still allows the virus to transmit,” said Bruno Canard, a coronavirus expert at the French national research institute CNRS.
Pfizer has promised a new vaccine within 100 days, but the roll-out will take longer and won’t be in place before spring, Canard said.
“Meanwhile, current vaccines protect against severe forms of Covid with the delta version.”
(Except for the title, this story has not been edited by NDTV staff and is published from a syndicated feed.)