NEW YORK - Pfizer expects a Covid-19 vaccine targeting the Omicron variant to be ready in March, the company's head said Monday.

Pfizer Chief Executive Officer Albert Bourla told CNBC that Pfizer is already manufacturing doses due to keen interest from governments, as authorities contend with huge Covid-19 infection counts, including large numbers of "breakthrough" Omicron cases in vaccinated populations.

"This vaccine will be ready in March," Bourla told the network. "I don't know if we will need it. I don't know if and how it will be used."

Bourla said the existing regime of two vaccine shots and a booster has provided "reasonable" protection against serious health effects from Omicron.

But a vaccine focused directly on the Omicron variant would also guard against breakthrough infections of a strain that has proven highly contagious, but has also resulted in many mild or asymptomatic cases.

In a separate interview with CNBC Monday, Moderna CEO Stephane Bancel said the company is developing a booster that could address Omicron and other emerging strains in the fall 2022.

"We are discussing with public health leaders around the world to decide what we think is the best strategy for a potential booster for the fall of 2022," Bancel told the network.

"We need to be careful to try to stay ahead of a virus and not behind the virus."

AFP