Pfizer chief executive Albert Bourla says an annual COVID-19 vaccine is preferable to more frequent booster shots in fighting the coronavirus pandemic.

Pfizer and BioNtech's COVID-19 vaccine is shown to be effective against severe disease and death caused by the heavily mutated Omicron variant but less effective in preventing transmission.

With cases soaring, some countries have expanded COVID-19 vaccine booster programs or shortened the gap between shots as governments scramble to shore up protection.

In an interview with Israel's N12 News, Bourla was asked whether he sees booster shots being administered every four to five months on a regular basis.

"This will not be a good scenario. What I'm hoping (is) that we will have a vaccine that you will have to do once a year," Bourla said in the interview on Saturday.

"Once a year - it is easier to convince people to do it. It is easier for people to remember.

"So from a public health perspective, it is an ideal situation. We are looking to see if we can create a vaccine that covers Omicron and doesn't forget the other variants and that could be a solution."

Bourla has said Pfizer could be ready to file for approval for a redesigned vaccine to fight Omicron, and mass produce it, as soon as March.

Citing three studies, the US Centers for Disease Control and Prevention (CDC) said on Friday that a third dose of an mRNA vaccine is key to fighting Omicron, providing 90 per cent protection against hospitalisation.

A preliminary study published by Israel's Sheba Medical Centre on Monday found that a fourth shot increases antibodies to even higher levels than the third but was likely not enough to fend off Omicron.

Nonetheless, a second booster was still advised for risk groups, Sheba said.