How does patent waiving work? It makes the patent invalid? Is it for a specific amount of time or do vaccines become CC0? What will happen when other countries

How does patent waiving work? It makes the patent invalid? Is it for a specific amount of time or do vaccines become CC0? What will happen when other countries start selling the vaccines (new covid vaccines will be the norm every year)? What about vaccine supplies ? Considering that the inventors are Biontech, oxford/AZ and Moderna (who won't enforce their patent), it seems like an easy decision for the US to make.