Moderna Chief Executive, Stephane Bancel, said Thursday the company expects more coronavirus disease variants to emerge in coming months as the Southern Hemisphere enters its fall and winter seasons, CNBC.

Bancel, speaking to investors on a first-quarter earnings call, said people will likely need to get booster shots of its two-dose vaccine as the virus circulates globally.

“New variants of concern continue to emerge around the world. And we believe that over the next six months, as the Southern Hemisphere enters the fall and winter, we could see more variants of concern emerge,” Bancel said. The Southern Hemisphere includes Africa, Australia, most of South America and parts of Asia. “We believe booster shots will be needed as we believe the virus is not going away.”

His comments come a day after the company announced a booster shot of its vaccine generated a promising immune response against the B.1.351 and P.1 variants first identified in South Africa and Brazil, respectively. The variants have since spread to other countries, including the U.S.

The data was preliminary and had not yet been reviewed by peers.

Moderna’s vaccine requires two doses given four weeks apart. Like Pfizer’s and Johnson & Johnson’s, the shot is highly effective against Covid, though company executives and officials now say they expect that strong protection to wane over time. Pfizer’s vaccine is also a two-dose regimen while the J&J immunization is just one jab.

Earlier Thursday, Moderna said sales of its successful vaccine helped drive its first quarterly profit ever.

Moderna’s vaccine generated US$1.7 billion in sales, according to its earnings report. The company also raised its 2021 sales forecast for its vaccine to US$19.2 billion, up from its previous forecast of US$18.4 billion. Bancel said the company is “actively engaged” in discussions and agreements for 2022 with all of the governments it is currently supplying.

Earlier this week, rival Pfizer also raised its vaccine sale forecast, predicting full-year sales of US$26 billion.

Moderna CEO Stephane Bancel expects more new variants of coronavirus