Pfizer starts clinical trial for omicron-specific Covid vaccine

Pfizer and BioNTech announced Tuesday that they have started a clinical trial testing a modified Covid-19 vaccine to protect against the supercontagious omicron variant of the coronavirus.

The drugmakers said they aim to enroll up to 1,420 healthy adults ages 18 to 55 in the trial, which will evaluate whether the omicron-specific vaccine is safe and generates a strong immune response.

The participants will be divided into three groups — fully vaccinated, fully vaccinated and boosted, and unvaccinated — which will determine whether they receive one, two or three doses of the modified vaccine.