Everyone? In the world?
Sigh...
At a 3.8 R0, if that number offered up by an epidemiologist is correct... the 1918 flu hit @ R0 of 2 hit 1/3rd the worlds population with no 1 day global mass travel so something almost twice as transmissible would infect many many more. Some isolated tribes in the Amazon, the scientists in Antarctica and the cannibals off the coast of India and the guys and gals on the space station... no... but the rest of us without natural immunity... almost everyone would have had it.