There are many other variations when you look at a situation like that. I'll let Dr. Gully, who was actually around at the time AND working on those issues, speak to it.
What is very clear is that when you look at the protection of health care workers, you start with a whole range of things: everything from sanitation to access to handwashing to gels that supplement handwashing. Personal protective equipment is only one piece of that. Much of the spread of SARS had nothing to do with the use of masks. It had to do with how we recognized or dealt with basic infection control procedures. They should be in place in all hospitals at all times, particularly for people who have potentially infectious diseases but even for those who don't, because you can't predict or tell who has the infectious disease.
We have abundant evidence now that when you focus on just those who you think are sick, as opposed to exercising good infection control procedures all the time, you may actually increase the risk to health care workers. That does not necessarily mean N95 masks. There are certain conditions for which they are recommended. At the same time, there is an appropriate responsibility in the local situation to assess that situation and take the precautions necessary. However, the evidence suggests that in the vast majority of those cases N95 masks do not offer any more protection than surgical masks.
Go ahead, Paul.