This is false. The DPA was invoked in order to a) block the export of certain raw materials in order to prioritise local production of vaccines and b) to compel drugmaker Merck to help produce its competitor Johnson & Johnson’s COVID-19 vaccine.[1] It does not block the export of vaccines. The White House clarified this last week as well.
[1] https://www.hhs.gov/about/news/2021/03/02/biden-administrati...