different manufactures could make the differences

https://www.pfizer.com/products/coronavirus/manufacturing-and-distribution 

Pfizer consistently and diligently monitors the supply of our medicines. We operate one of the most sophisticated supply chain systems in the industry, with over 40 Pfizer-owned sites and over 200 suppliers globally, which provides capacity and redundancy as needed. Our manufacturing and supply chain professionals have been working non-stop to ensure that the global supply of Pfizer medicines continue to be available to patients. We have implemented an unprecedented and comprehensive preparedness plan to control our site operations and will continue to provide timely updates if there is any new information to be shared.