My time is limited. I have another question, but not specifically for you.
Going back to Professor Attaran, you mentioned that we could ask you questions about yesterday's meeting.
I asked Dr. Tam about her flip-flop on the use of masks. Up until early April, Dr. Tam stated that an asymptomatic person shouldn't wear a mask. It didn't work. It might even be harmful. Then on April 6, she changed her mind and said that a mask was good for additional protection.
Her response to my question on why her message changed was that, apparently, new evidence had come to light.
As this was a respiratory pathogen, I imagine that out of the abundance of caution, masks would have been helpful right from the beginning.
In your opinion, what sort of new evidence has come to light over the course of this pandemic that would substantively change the way we consider the effectiveness of masks as prophylactics?