The U.S. drugmaker said it expects sales of $13.5 billion from the vaccine for 2023, below Refinitiv estimates of $14.39 billion, and projected $8 billion in sales of its antiviral pill, Paxlovid, short of $10.33 billion the Street expects.

The lower forecast casts uncertainty over the future of Pfizer's biggest selling products, which are expected to come under pressure this year as government spending on COVID vaccines and treatments declines.

The drugmaker has been hoping to offer its vaccine through the private market in the United States and other markets as government-backed vaccination campaigns for original shots near their end.