Scientists working in BSL-4 are required to wear a full-body suite that gives them no direct contact with the viruses they are observing and experimenting on. The laboratory itself is usually separated from the rest of the other laboratories, and has a high security level. In the movie, they had ramps and hallways with very large security doors and people that stood guard, that led to their BSL-4 laboratory.
If I was a scientist working at the CDC I would want a laboratory