Health authorities, hospitals and pharmaceutical companies are storing Covid-19 vaccines in secure, undisclosed locations and taking other steps to protect the shots against a looming threat: theft.

As the leading vaccine candidates advance closer to use, vaccine makers such as Pfizer Inc. are deploying GPS software for tracking distribution and plotting fake shipments in dummy trucks to confuse criminals. Glassmaker Corning Inc. is equipping vials with black-light verification to curb counterfeiting. And some hospitals expected...