Syringes with needles are seen in front of a displayed Moderna logo in this illustration taken November 27, 2021.
Syringes with needles are seen in front of a displayed Moderna logo in this illustration taken November 27, 2021. Reuters / DADO RUVIC

Moderna Inc on Wednesday maintained its full-year COVID-19 vaccine sales forecast of $21 billion as canceled orders from low- and middle-income nations through the COVAX program offset gains from new booster dose orders.

Moderna shares jumped nearly 17% in morning trading after the company also announced a $3 billion share buyback plan.

Moderna has begun producing a redesigned booster shot targeting both the original coronavirus as well as the BA.4 and BA.5 Omicron subvariants.

It signed a $1.74 billion deal with the U.S. government last week for 66 million doses to be available this fall and winter, if cleared by health regulators.

Despite the contract, Moderna kept its sales forecast unchanged as doses earmarked for the COVAX vaccine sharing program remain unallocated due to low demand.

"It's because of COVAX," Chief Executive Stephane Bancel said in an interview. "COVAX does not want the doses that they have ordered."

Moderna and rival Pfizer Inc have been banking on recurring booster doses, including an Omicron-tailored version, to garner more vaccine contracts with higher-income countries.

"We do believe the majority of the market demand is captured in this $21 billion. That being said, we continue to work with countries around the world on potential additional orders," said Chief Commercial Officer Arpa Garay.

Other countries are considering an earlier version of the booster shot designed to target the BA.1 Omicron variant that led to a record surge in infections last winter, rather than the currently dominant BA.5 or related BA.4.

Those shots had been in production already and would be available sooner, Bancel said.

"There are plenty of countries around the world that would rather start early - as early as August," he added.

"Some of those countries have said they would rather start with the BA.1 now and then go to BA.4 later versus just waiting and hoping."

Some countries could authorize the retooled BA.1 boosters within the next few weeks, the CEO said.

Moderna reported $4.5 billion in COVID vaccine sales in the second quarter. It took a $499 million charge related to vaccines that have expired.

Moderna shares were up 16.7% at $187.60 but are off about 30% for the year to date.