By September 1968, it had infected Marines returning to the States from the Vietnam War. By mid-December, the Hong Kong flu had arrived in all 50 states.
But schools were not shut down nationwide, other than a few dozen because of too many sick teachers. Face masks weren’t required or even common. Though Woodstock was not held during the peak months of the H3N2 pandemic (the first wave ended by early March 1969, and it didn’t flare up again until November of that year), the festival went ahead when the virus was still active and had no known cure.