He told CNN on Sunday that the virus could still have an impact into 2022, and that the nation won't be "closer to normal" until the end of next summer.
2021 looks tough, Gates said.
"Well, sadly, the next four to six months could be the worst of the epidemic," Gates told CNN host Jake Tapper, noting that the IHME (Institute for Health Metrics and Evaluation at the University of Washington) forecast shows over 200,000 additional deaths in the US over that time period.
Wearing masks and not mixing with other households could help prevent a large percentage of those deaths, he said.
"But even through early 2022, unless we help other countries get rid of this disease, and we get high vaccination rates in our country, the risk of reintroduction will be there," he warned.
Tapper asked when Gates envisioned things returning to the "normal" of January 2019, meaning no masks or social distancing required.
"Certainly by the summer, we'll be way closer to normal than we are now," Gates said, noting that big public gatherings could still be restricted even by summer. But Americans should stay hopeful: "We have a chance, if we manage (vaccinations) well, to get back to normal."
When asked if one of the vaccines was better than the other, Gates unequivocally said no, and that he was "super happy" with all of the vaccines announced. And he's willing to back that up, noting that he would, like former presidents Bill Clinton, Barack Obama and George W. Bush, and president-elect Joe Biden, get the vaccine publicly -- though he noted he would wait his turn and not pull any strings to receive a vaccine early.
Gates previously said that "almost all" coronavirus vaccines.