“During the deadly 1918 Pandemic, the first wave, which hit in the spring, was mild,” Grant said. “But the disease roared back in a more virulent form in the fall.”

Authorities are closely monitoring what the pandemic is doing now in the Southern Hemisphere, where the annual flu season is under way.

“What happens there may give us an idea of what to expect here this fall with seasonal flu,” Grant said. “We hope a vaccine will be available by then, but there is no guarantee.”