Pharmaceutical companies Pfizer and BioNTech on Tuesday said that they have started a clinical study to test a version of their Covid-19 vaccine specifically designed to target the Omicron variant.

The study will be conducted on up to 1,420 participants from the ages of 18 years to 55 years.

Kathrin Jansen, the Head of Vaccine Research and Development at Pfizer, said that while current data shows that three doses of the current vaccine provide protection against severe disease due to Omicron, there is a need to be prepared if this protection wanes over time.

“Staying vigilant against the virus requires us to identify new approaches for people to maintain a high level of protection, and we believe developing and investigating variant-based vaccines, like this one, are essential in our efforts towards this goal,” she said.

BioNTech CEO Ugur Sahin said that protection offered by the current vaccine against mild to moderate symptoms wanes more rapidly with Omicron than with earlier strains. “This study is part of our science-based approach to develop a variant-based vaccine that achieves a similar level of protection against Omicron as it did with earlier variants but with longer duration of protection,” Sahin said.

The participants will be divided into three groups – one that has received two doses of the current Pfizer-BioNTech vaccine, one that has received three doses, and another that has not received any vaccine.

The first group will get one or two doses of the Omicron-specific vaccine, while the second group will get one dose of either the current vaccine or the Omicron-specific vaccine. The third group will receive three doses of the Omicron-based vaccine.

Pfizer and BioNTech began work towards an Omicron-specific Covid-19 vaccine on November 25.

On December 8, data released by the companies showed that a third dose of their Covid-19 vaccine neutralises the Omicron variant of the coronavirus.

The study had found that people who received only two shots of the vaccine showed more than a 25-fold reduction in antibodies against the Omicron variant compared to the original strain of Covid-19. On the other hand, those who received a third dose had similar number of antibodies against Omicron as against the original variant.

On January 11, a technical advisory group of the World Health Organization had said that it encourages coronavirus vaccine manufacturers to “generate and provide data on performance of current and Omicron-specific COVID-19 vaccines.” It said that this data will help to take decisions on changes to the composition of vaccines, if required.