While it’s still summer in America, it’s winter in Australia and the number of flu cases there have been rising sharply, especially among children. Scientists in the U.S. are keeping an eye on what’s happening “down under” as we may experience similar health patterns here as fall approaches.

“We closely monitor what happens in countries throughout the Southern Hemisphere this time of year, just to see what’s happening during their flu season,” said Carrie Reed, chief of the Influenza Division of the U.S. Centers for Disease Control and Prevention’s Epidemiology and Prevention Branch. “It’s not always a predictor of what’s going to happen here the next season, but yes, we do.”

According to CNN, the Centers for Disease Control and Prevention (CDC) estimates that flu resulted in between 9 million to 41 million illnesses, 140,000 to 710,000 hospitalizations and 12,000-52,000 deaths annually between 2010 and 2020. It costs the U.S. about $10.4 billion in direct costs for hospitalizations and outpatient visits, and that’s only for adults.

Reed said that the CDC has a formal effort in collaboration with academic groups and private industry that specialize in flu forecasting but acknowledges that each year, the flu season is a little different, so every year presents a challenge.

Experts say that flu is difficult to predict because human behavior is erratic. During the pandemic, the cases of influenza plummeted because people wore masks and were careful socializing.

But humans do have predictable behavior that can influence the spread of flu. Children will go to school, and families will gather over the holidays. If influencers like Taylor Swift start to wear masks in a city with high flu numbers, her followers may do the same and that behavior change can cause numbers to drop, says CNN.

So, it’s not so simple to predict how severe this year’s flu season will be, says Reed.

“It’s a mix of human behavior, social interactions, mobility, but also weather humidity, and population immunity,” she said.

And this coming fall may present an even more intricate challenge to stay well, says Dr. William Schaffner, a professor in the Division of Infectious Disease at Vanderbilt University Medical Center and medical director of the National Foundation for Infectious Diseases.

“Looking at this fall, we are going to have a special challenge because, in addition to urging everyone to get their annual influenza vaccine, we’re going to have a new updated COVID-19 vaccine that will be available. And in addition to that, two new RSV vaccines have just been licensed.

“And in a week and a half or so, the CDC’s advisory committee will provide recommendations as to who ought to get that vaccine, and it’s going to be at least older adults. So, some people will be recommended to get not one, not just two, but three vaccines,” he said.

It’s perfectly fine to get your COVID-19 vaccine and the flu shot at the same time.

“The flu is nasty, and the best way to protect yourself is with the vaccine,” says Dr. Keith Roach, an internist at New York-Presbyterian/Weill Cornell Medical Center. “And with COVID-19 still out there, it is perfectly safe to get the flu shot and updated omicron booster at the same time.”

Roach told Health Matters that many experts are predicting a severe flu season because there may be less overall population immunity due to low flu season the last few years. “But to protect yourself and loved ones, get your flu shot and COVID-19 boosters and continue to be cautious this winter.”