Pfizer Inc (NYSE: PFE) and BioNTech SE (NASDAQ: BNTX) have started a clinical trial to test a new version of their vaccine specifically designed to target the COVID-19 Omicron variant.

• Pfizer has said that a two-dose regimen of the original vaccine may not be sufficient to protect against infection from the omicron variant.

• Related: Pfizer/BioNTech COVID-19 Shot Provides Partial Protection Against Omicron, Study Shows.

• The companies plan to test the immune response generated by the Omicron-based vaccine both as a three-shot regimen in unvaccinated people and as a booster shot for people who already received two doses of their original vaccine.

• They are also testing a fourth dose of the current vaccine against a fourth dose of the Omicron-based vaccine in people who received their third dose of the Pfizer/BioNTech vaccine three to six months earlier.

• The companies plan to study the safety and tolerability of the shots in the more than 1,400 people who will be enrolled in the trial.

• "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 help address Omicron and new variants in the future potentially," said Pfizer's head of vaccine R&D, Kathrin Jansen.

• Also See: 4 Shots Of Pfizer COVID-19 Vaccine Not Enough To Prevent Omicron Infection, Say Israeli Researchers.

• Price Action: BNTX shares are up 3.66% at $156.50, PFE stock is down 0.27% at $51.40 during the premarket session on Tuesday's last check.

See more from Benzinga

• Pfizer, AstraZeneca or J&J COVID-19 Shots Boost Sinovac Regime, Brazilian Study Shows

• Arcturus Therapeutics' COVID-19 Booster Clinical Trial Show Encouraging Neutralizing Antibody Responses

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