MASSACHUSETTS, NEW ENGLAND (BLOOMBERG) - The pandemic could start moving into an endemic phase in 2022, though countries will need to stay vigilant as the Omicron variant spreads, according to Moderna co-founder and chairman Noubar Afeyan.

While some countries slowly begin to consider treating Covid-19 as an endemic disease, like the flu, World Health Organisation officials have said it is too early to make that call as cases surge.

"2022 may be the year that the pandemic enters an endemic phase, but it really depends on what happens and the decisions that are made across the world," Dr Afeyan said in a Bloomberg Television interview on Friday. Although Omicron is highly transmissible, "on the other hand it's having a lesser effect in terms of seriousness of disease".

Moderna's Omicron-specific booster shot could enter into human trials within weeks, he said, reiterating comments that chief executive officer Stephane Bancel made earlier this week.

The CEO said he expected another booster would be needed in the fall, and it is likely to contain a component tailored to Omicron.

"We will be ready with our testing starting in weeks," Dr Afeyan said on Friday. "Whether we need a booster rather in the spring than the fall is something that we're going to have to work with officials all around the world to sort out."

Shares of Moderna declined 3.3 per cent in pre-market trading in New York.

Moderna, along with Pfizer and its partner BioNTech, developed highly effective Covid-19 vaccines based on messenger RNA technology. Moderna said earlier this week that it has signed vaccine purchase agreements worth US$18.5 billion (S$25 billion) for this year, along with options for another US$3.5 billion, including booster shots.