So, in the emails early on, Fauci did say that there wasn't good reason for everyone to wear masks. That was because, at the time, they were unaware of a number of variables that existed with COVID-19.

If you look at scientific information as it accumulates, what's going on in January and February, what you know as a fact, as data, guides what you tell people and your policies. If March, April, May occur, you accumulate a lot more information and you modify and adjust your opinion and your recommendation based on the current science and current data.