PfizerAnd BioNTechAs concerns mount that vaccines that target the omicron Covid strain are not protecting against mild infections, the clinical study was initiated Tuesday.

Albert Bourla from Pfizer told CNBC that the company plans to have a vaccine for omicron available by March. Bourla stated that the vaccine will also be used to target other Covid variants currently in circulation.

Ugur Sahin, CEO of BioNTech said that there is growing evidence suggesting that the effectiveness of current vaccines against infection and moderate-to-severe disease from the omicron virus are decreasing faster than previous strains. Sahin announced Tuesday in a statement that they are working to produce a vaccine which provides long-term protection from omicron.

According to the Centers for Disease Control and Prevention, a new study was published by them last week. It found that Pfizer’s booster shot prevented omicron-related hospitalizations at 90% within fourteen days.

According to the U.K. Health Security Agency, booster doses can also be effective in preventing symptoms from omicron up to 75% two to four weeks following the third shot. However, boosters lose their effectiveness in protecting against symptoms after about 10 to 14 weeks.

Kathrin Jansen (head of vaccine development at Pfizer) stated that current research shows boosters provide high protection against serious disease and hospitalizations. However, she also said that real-world data supports this assertion.

Pfizer’s and BioNTech will be evaluating up to 1,420 participants in their clinical study.

Bourla said earlier this month that he didn’t know when or if an Omicron vaccine would be needed. Pfizer has the vaccine in stock as many countries demand it, Bourla said.

“The hope is that we will achieve something that will have way, way better protection — particularly against infections,” Bourla said.

There are many mutations in the Omicron variant, including some that affect the spike protein which the virus uses as a weapon to attack human cells. The spike is the target of the current vaccines that were developed against the original strain in 2020. The virus becomes harder to stop with vaccine-induced antibodies as it mutates more and more from its original form in Wuhan, China.

Omicron was first discovered in Botswana in November and South Africa in December. It has since spread quicker than other variants, creating a new wave of infections around the globe.

World Health Organization Director-General Tedros Adhanom Ghebreyesus said Monday there have been more than 80 million Covid cases reported to WHO since the omicron variant was identified just nine weeks ago — more than were reported in all of 2020.

Omicron is generally less dangerous than the delta strain. Omicron is causing milder breakthrough infections than the original strain that vaccines were created to combat. This raises concerns about disruptions in essential services due to increased calls for help.