Nina Pham was self-monitoring and caught the symptoms early. Nobody got it from her.
Amber Vinson was self-monitoring and even traveled while carrying the virus. Nobody got it from her.
The Spanish nurse monitored for symptoms, and nobody got it from her.
It is too early to tell for Dr. Spencer, but he flew, went bowling, and rode the subway. Assuming nobody gets it from him, then the presumption that people are not contagious when they don't show symptoms seems to be holding up.
Monitoring for symptoms seems be catching these cases early, before they spread.
I'd really like to see the procedures and equipment enhanced so that no health care worker gets the virus from someone they treat. They are treating people who are highly symptomatic and therefore highly contagious. But we should be able to manage that risk better, IMHO. This seems like a better trade-off of resources than simply isolating all health care workers, regardless of lack of symptoms. There are serious problems with isolating health care workers, and it's easy to overlook the cost of doing so. It takes MANY people to treat a single patient, and it's just not feasible to have all of them out of service for weeks at a time. It doesn't scale well.
If there is evidence that monitoring for symptoms is not working, then we should change that. Of course.