The problem is patients only get this at the point that they require hospitalization.
It should be as easy to get a short-term dose of this (unlikely to cause severe side effects) as it is to get a seasonal flu shot, and people should be advised to take it for two weeks (or whatever) at the onset of symptoms, or even as a prophylactic if they know they were exposed.
A "while" here means months, or even years. In fact, many people with Lupus or RA take this for years.