Pfizer and BioNTech will start a clinical trial for an Omicron-specific vaccine. The study will include three cohorts of healthy adult participants ranging from ages 18 to 55. The first group will include those who had two doses of the Pfizer vaccine at least 90 to 180 days ahead of the study. They will receive either one or two doses of the Omicron vaccine. The second group will be made of participants who have had three doses of the Pfizer vaccine, also at least 90-180 days prior. This group will be given one dose of the Omicron-specific vaccine. Finally, the third group will include participants who have not received any vaccines for Covid-19. They will get three doses of the Omicron vaccine. "While current research and real-world data show that boosters continue to provide a high level of protection against severe disease and hospitalization with Omicron, we recognize 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," Pfizer Senior Vice President and Head of Vaccine Research and Development Kathrin Jansen said in a release. The production of the new vaccine will not affect the number of regular Covid vaccines slated to be produced this year. Pfizer and BioNTech also stress that those who have received the booster are already highly protected from any serious symptoms of Omicron, and should be for up to four months after receiving the dose. New Covid-19 cases are finally decreasing in the U.S. following a massive spike around the holidays, but the numbers are still high. New cases are still above 668,000 per day.