The European Commission is assessing potential new locations for the EMA, but the decision rests with EU leaders who will try to reach a deal at their next summit in October.
Milan, Copenhagen, Athens, Amsterdam and Barcelona are among the cities seeking to host the EMA, with Milan seen as a possible frontrunner.
For the five most popular locations, staff retention rates would range between 65 and 81 percent, allowing for approval of new drugs and safety monitoring to largely continue, but with possible delays in some initiatives such as tackling antimicrobial resistance, the agency said.
If one of the five lower-ranking cities with a projected staff retention rate of 51-60 percent was picked, new drug approval as well as implementation of new legislation would be delayed, the EMA said.
The consequences of choosing one of the nine lowest-ranking locations would be even more dire, exposing patients to serious risk due to delays in drug approval and poor safety monitoring, the agency said.