With Labor Day 2020 in the rearview mirror, the U.S. is heading toward the start of fall and flu season.

It comes as the U.S. passes more than 189,000 known COVID-related deaths, according to Johns Hopkins University.

Americans are advised to roll up their sleeves and get a flu shot this year. "The fall and winter of 2020 and 2021 are going to be probably one of the most difficult times that we experienced in American public health," says Dr. Robert Redfield, Director, US Centers for Disease Control and Prevention.

While some parts of the U.S. are seeing new coronavirus cases drop, experts say not to let guard down. "Unfortunately we're already at a much higher level than we were in the weeks before the July 4th holiday so I don't think it'll take us much to really bring us back up to 70,000 new cases a day," says Dr. Peter Hotez, of Baylor College of Medicine.

Medical experts are working on a COVID-19 vaccine and the White House says it may be ready before the end of the year. "We'll have the vaccine very soon, maybe before a very special date. You know what date I'm talking about," said President Donald Trump on Monday.

Democratic presidential candidate Joe Biden is leery about the president's claim. "He says so many things that aren't true, I'm worried if we really do have a good vaccine, people will be reluctant to take it."

Experts say a vaccine is unlikely before 2021, and health officials stress the importance of staying vigilant. "Many of the physical distancing and public health measures that have been put in place, which keeps people apart, may have actually played a role in reducing circulation of influenza," says Maria Van Kerkhove, WHO Covid-19 Technical Lead.