Pfizer and BioNTech announced Tuesday the start of recruitment for adult clinical trials to ascertain the immune response of the human body already immunized against covid-19 with a vaccine specifically targeting the omicron variant.

"This study takes place within the framework of our scientific approach, which aims to design targeted vaccines for the variants that can develop similar levels of protection against omicron as for the variants that appeared earlier, but with a longer duration of protection," specified the head of BioNTech, Ugur Sahin.

The head of vaccines at Pfizer, Kathrin Jansen, said that although booster doses of the original vaccine protect against the severe forms of the new variant, the company prefers to act out of an overzealousness.

"We recognize the importance of being prepared in case this protection diminishes over time and to help address omicron and other variants in the future," he said.

The protection of the initial vaccine against the mild or moderate forms of covid-19 seems to disappear more quickly against omicron, assumes BioNTech head Ugur Sahin.

The clinical trial covers 1,420 people, aged 18 to 55. The trial participants are divided into three groups.

The first includes people who received two doses of the Pfizer-BioNTech vaccine 90 to 180 days earlier, and who will receive one or two injections of the new tested serum.

The second group consists of people who received their third dose in the same period and who will receive a new dose of the initial vaccine or a dose of the designed omicron vaccine.

The third comprises people who have not received any covid-19 vaccine and who will receive three doses of the one specifically targeting Omicron.

Several countries have begun to report a decrease in the number of cases of the wave caused by Omicron, the most transmissible variant detected at this stage, although the number of infections worldwide continues to rise.