(NEXSTAR) —  Doctors are paying close attention to warning signs out of the Southern Hemisphere that may indicate a rough flu season is looming in the United States.

Australia’s flu season usually peaks during their winter, in July or August, giving us a preview of what we may be able to expect during our peak flu season in the winter months. The country just experienced its fifth worst flu season in history, said Dr. Andrew Pekosz, a virologist with the Johns Hopkins Bloomberg School of Public Health, in a recent media briefing.

Two things made the season especially severe, Pekosz explained. First, the season started earlier than usual, catching some people off guard. Here at home, the Centers for Disease Control and Prevention told NBC News they are staying “very alert” for signs of an early flu spike.

“The first thing that we’ll look for is when local public health agencies start to report cases of influenza,” Pekosz said. “We shouldn’t see influenza until November or December at the earliest, and it shouldn’t peak until January or February.”

But if we start to see significant case numbers being reported between September and November, Pekosz said, “That’ll be the first sign that influenza is coming here earlier.”

If flu season starts earlier, you may want to consider getting vaccinated earlier.

“It’s always difficult to time vaccinations correctly,” Pekosz admitted, since we can’t easily tell when cases may spike in our communities. “What I would do, particularly if you’re in a high-risk group, I would see about influenza vaccine availability in your area. The vaccine usually rolls out primarily in October, though some pharmacies may have it right now.”

The other aspect that made influenza particularly devastating in Australia this year is how hard it hit children and young people. A lot of children haven’t had much exposure to the virus in recent years thanks to measures put in place to prevent COVID-19 spread. Their immune systems proved especially vulnerable in Australia, joining the elderly as groups at high risk for serious illness. NBC News reports kids ages 5 to 9 reported the most cases, followed by kids under 4.

Pekosz said health officials in the U.S. will be paying close attention to who is being admitted to the hospital for influenza once infections begin to assess if children here are getting sicker than in years prior.

The good news, Pekosz said, is he believes the vaccine should be a good match for the flu strain we expect to see circulating. (Australia health officials, however, said it is too early to assess whether that was the case.) The CDC recommends everyone older than 6 months old get vaccinated against influenza annually (with a few exceptions).

“I would think about the influenza vaccine the same way you’re thinking about the bivalent COVID-19 vaccine,” Pekosz said. “Both of those are needed, both of those should be scheduled as soon as possible, and ideally at the same time, so that one doesn’t fall into the trap of getting one and then forgetting to come back for the other.”

Only about half of Americans got the flu vaccine in the 2020-2021 flu season, according to CDC data.