The fall COVID-19 vaccine season is starting slowly for Pfizer, with U.S. sales of its Comirnaty shots sinking 25% after federal regulators narrowed recommendations on who should get them.

Shares of Metsera fell over 15% in premarket trading on Monday, after the weight-loss drug developer accepted a sweetened offer from Pfizer to end a fierce bidding war between the pharma giant and Danish rival Novo Nordisk .

Novo Nordisk's late bid to hijack Pfizer's takeover of US obesity biotech Metsera marks an aggressive shift from the Danish drugmaker as it seeks to regain ground in the weight-loss drug market under a new CEO and board https://t.co/6Qz7tNsm9x pic.twitter.com/EvYvxeoaeC

FILE - The Pfizer logo is displayed at the company's headquarters, Friday, Feb. 5, 2021, in New York. (AP Photo/Mark Lennihan, File) WASHINGTON (AP) — Drugmaker Pfizer has agreed to lower drug costs and invest $70 billion in U.S. manufacturing under a ...

In a press release on Friday, Metsera said Pfizer had made an improved offer to acquire it for up to $86.25 per share, in a deal worth around $10 billion. Metsera said its board “unanimously recommends that… stockholders approve the adoption of the amended Pfizer merger agreement and approve the merger.”