Some of this work is ongoing already. There is work, studies, going on with some individuals who have had an infection and recovered from the infection. What we are learning from them is how long immunity lasts, what effective mechanisms play a role in protection and how those can be built into the vaccine research we are doing.
In terms of how long one would have to wait, you essentially develop a very strong immune response after infection. Typically within a few weeks you have a good adaptive immune response and that typically lasts months and hopefully longer. That is what we don't know at the moment. Certainly it would be great to study some of this. I think ethically it will have to be specifically addressed whether you can expose these individuals to the virus or put them in a higher-risk situation, but certainly those things are very important. We can learn a lot from people who have recovered from this infection.