Australia's flu season was a doozy — and that's not a good sign for us.

From Prevention magazine.

By Korin Miller

Flu season has almost always been a predictable part of every winter, but the COVID-19 pandemic threw things out of whack.

The 2020-2021 flu season was practically non-existent due to COVID-19 precautions and lockdowns, and last year’s flu season was definitely mild compared to pre-pandemic years.

But many health experts are predicting the 2022-2023 flu season will be a severe one. A big reason? Australia, which is in the southern hemisphere and experiences its flu season before ours, had a doozy of a flu season.

The country had its worst flu season in five years, with cases being three times higher than average according to government surveillance reports. Flu cases also peaked about two months earlier than usual, signaling the country had an early onslaught of the flu.

"The Southern Hemisphere has had a pretty bad flu season, and it came on early," Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, told Bloomberg late last month. "Influenza, as we all have experienced over many years, can be a serious disease — particularly when you have a bad season."

Why might this flu season be bad and what can you do to prepare now? Infectious disease experts break it down.

Why might this year’s flu season be bad?
Infectious disease and public health experts in the Northern hemisphere generally look to what’s happening in the Southern hemisphere as a predictor of where things will go during our winter, explained Dr. Amesh A. Adalja, infectious disease expert and senior scholar at the Johns Hopkins Center for Health Security.

"The planet has two hemispheres which have opposite respiratory viral seasons," he said. "Therefore, Australia’s flu season — which is just ending — is often predictive of what will happen in the Northern hemisphere."

Based on what just happened in Australia "it does appear that we will not be spared another flu season," Adalja said.

Dr. William Schaffner, an infectious disease specialist and professor at the Vanderbilt University School of Medicine, agrees.

"Although what happens in the Southern hemisphere doesn't always predict directly what will happen here, we are well advised to be prepared," Schaffner said.

It's also concerning that many people haven’t been exposed to the flu over the past few years due to COVID-19 restrictions and low circulating levels of the flu, said Dr. Thomas Russo, professor and chief of infectious disease at the University at Buffalo in New York.

"Immunity to respiratory viruses, including the flu, wanes over time," Russo said. "People have not seen the virus naturally for a couple of years and many individuals don’t get the flu vaccine."

That, he said, raises the risk that people who are unvaccinated against the flu will develop more severe cases if they do happen to get infected.

This is the first winter where COVID-19 restrictions have been lifted in most areas of the country, including on public transportation, Russo said.

"People are interacting closely again and there are very few mandates," he said. "That's a set-up for increased transmission of influenza and other respiratory viruses."

How to protect yourself against the flu now
Flu season in the U.S. generally picks up in October, peaks between December and February, and can last until May, according to the Centers for Disease Control and Prevention (CDC). That’s why it's a good idea to get your flu shot before Halloween, if you can, Schaffner said.

"The most important thing people can do is to get vaccinated against influenza," he said. "People have been so preoccupied with COVID that they've forgotten about influenza, but the flu can also be severe."

It's also not a bad idea to stock up on high-quality masks, like N95s, Russo said. "Masks work at preventing COVID-19 and the flu," he said.

If you're considered high risk for serious complications of the flu and cases start to creep up in your area, Schaffner recommends masking up in crowded indoor spaces.

Overall, experts shouldn't expect the mild flu seasons we’ve enjoyed lately to last.

"I think we will definitely get a more significant flu season than last year," Russo said. "It's important to be ready."