From the article:
Prashant Yadav, who studies health care supply chains at the Center for Global Development in Washington, said Moderna should be able to make factory adjustments to produce fuller vials fairly quickly.
If too many doses are added to a vial, it can break. Moderna officials ran a series of tests and determined the upper limit was 15. Unlike Pfizer, whose manufacturing is geared to a vial limited to about six doses, Moderna’s was big enough to hold the industry standard of 10 doses, in addition to some more, according to people familiar with the companies’ operations.
