Clinical trials have started to test a new version of the Pfizer-BioNTech vaccine designed to fight the Omicron variant.
The companies plan to test the immune response generated by the formulation of a three-shot regimen in unvaccinated people and as a booster shot for people who have already received two doses of their original Covid-19 vaccine.
They will also test a fourth dose of the current vaccine against a fourth dose of the Omicron-based one in people who received their third dose of the Pfizer-BioNTech vaccine three to six months earlier.
“Staying vigilant against the virus requires us to identify new approaches for people to maintain a high level of protection,” Pfizer’s head of vaccine research and development, Kathrin Jansen, said.
“We believe developing and investigating variant-based vaccines, like this one, are essential in our efforts towards this goal.”
About 1,400 people will be involved in the new trials testing the safety and tolerability of the shots.
“While current research and real-world data show that boosters continue to provide a high level of protection against severe disease and hospitalisation with Omicron, we recognise the need to be prepared in the event this protection wanes over time and to potentially help address Omicron and new variants in the future,” Ms Jansen said.
Pfizer has said a two-dose regimen of the original vaccine may not be sufficient to protect against infection from the Omicron variant, and that protection against hospital admissions and deaths may be waning.
The US Centres for Disease Control and Prevention said a third dose of an mRNA vaccine, such as the Pfizer-BioNTech vaccine, has provided 90 per cent protection against hospital admission for Covid.
The Omicron variant has replaced the Delta variant as the dominant lineage in many parts of the world and Omicron itself is mutating into subforms, of which one, BA2, is of particular concern.
In Europe, England has ended a partial lockdown to tackle the Omicron wave, which caused a record number of new cases.
Infections have also soared in Germany. Health chiefs there expect the rise to continue into February.
France has recorded record cases and the Netherlands has brought in a lockdown.