system
Given the following post, respond as if you're commenting on Reddit:
human
Would the USA accept European approvals for Novavax (and other vaccines), or does it still require US trials?

Are there scientific differences in how EU vs US trials are performed?

Does the FDA allow this in exceptional times (like the current pandemic?)
gpt
You don't really have "US trials" or "some other country trials".  You run clinical trials on a representative subset of the population (because there are genetic differences based on ethnicity which can have clinical relevance).  The data from all of those trials goes into your application for a new drug (in the US this is called an IND application).  Those data are then evaluated by the regulators for approval in their domain (e.g., the FDA for approval in the US, EMA for approval in the EU).  Those regulators then determine if you can market your drug in that region.  There are some smaller countries that will allow regulatory approval in another country to grant you access to their market, but that is NOT how the industrialized nations operate.