Sir Patrick Vallance says it's not uncommon for leaders to lack "scientific understanding"

Vallance told the committee it was "hard work" at times trying to get Johnson to understand certain information.

He also discussed public health advisory groups Sage and Spi-B, and how leaks into the media from certain members created an issue.

Another diary entry presented to the inquiry, dating to January 2020, recorded Vallance writing that it was not "inevitable" that Covid would spread.