End of social distancing, masking, and other COVID-19 pandemic mitigations may lead to more severe flu-like infections in northern hemisphere, experts say

Clinical laboratory professionals in the United States and Canada should prepare now for a severe flu season. That is according to infectious disease experts at Johns Hopkin’s Center for Health Security who predict the rise in influenza (flu) cases in Australia signals what will likely be higher than normal numbers of flu-like infections starting this fall in the Northern Hemisphere.

As a Southern Hemisphere nation, Australia experiences winter from June through August. The land down under just concluded its worst flu season in five years. The flu arrived earlier than usual and was severe. Surveillance reports from the Aussie government’s Department of Health and Aged Care noted that influenza-like illness (ILI) peaked in May and June, but that starting in mid-April 2022 the weekly number of flu cases exceeded the five-year average.

If the same increase in flu cases happens here, healthcare systems and clinical laboratories already burdened with continuing COVID-19 testing and increasing demand for monkeypox testing could find the strain unbearable.

Amesh Adalja, MD

Amesh Adalja, MD (above), Infectious Disease Expert and Senior Scholar at the Johns Hopkin’s Center for Health Security, told Prevention that Australia’s flu season is typically a harbinger of what will follow in the US, Canada, and other Northern Hemisphere countries. “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.” Clinical laboratories in the United States should review their preparations as North America enters its influenza season. (Photo copyright: Johns Hopkins Bloomberg School of Public Health.)

Consequences of Decline in Flu Vaccinations and Social Distancing, Masks

The New York Times noted that in 2017, when Australia suffered through its worst flu season since modern surveillance techniques were adopted, the US experienced a deadly 2017-2018 flu season a half-year later that took an estimated 79,000 lives.

While the number of flu cases in this country is currently low, according to the weekly US Centers for Disease Control and Prevention’s (CDC) “Flu View,” that is expected to change as temperatures cool.

During the height of the COVID-19 pandemic in the US, influenza was nearly nonexistent. Pandemic-mitigation efforts such as masking, social distancing, and quarantining slowed the spread of the annual respiratory illness. But pandemic mitigation efforts are no longer the norm.

“Many have stopped masking,” said Abinash Virk MD, an Infectious Diseases Specialist at Mayo Clinic College of Medicine and Science, in a Mayo Clinic news blog that urged patients to get vaccinated for flu. “For the large part, we will see the re-emergence of influenza in the winter. In comparison, in 2020 winter … there was literally no influenza. But now that has all changed.”

Diminished Immunity Will Lead to More Severe Flu Cases

A CDC report published in July also noted that last winter’s flu season broke from the traditional pattern of arrival of the flu in the fall followed by a peak in cases in February.

During the 2021-22 season, influenza activity began to increase in November and remained elevated until mid-June. It featured two distinct waves, with A(H3N2) viruses predominating for the entire season. But the overall case counts were the lowest in at least 25 years preceding the COVID-19 pandemic.

Thomas Russo, MD, Professor and Chief of Infectious Disease at the University at Buffalo in New York, said the past two mild flu seasons could set the stage for a difficult year in 2022-23.

“Immunity to respiratory viruses, including the flu, wanes over time,” Russo told Prevention. “People have not seen the virus naturally for a couple of years and many individuals don’t get the flu vaccine.” That, he says, raises the risk that people who are unvaccinated against the flu will develop more severe cases if they do happen to get infected.

“People are interacting closely again and there are very few mandates,” he added. “That’s a set-up for increased transmission of influenza and other respiratory viruses.”

Anthony Fauci, MD, Director of the National Institute of Allergy and Infectious Diseases (NIAID), warns the US could see higher than normal rates of influenza while COVID-19 is still circulating widely.

“The Southern Hemisphere has had a pretty bad flu season, and it came on early,” Fauci, told Bloomberg in late August. “Influenza, as we all have experienced over many years, can be a serious disease, particularly when you have a bad season.”

CNN reported that US government modeling predicts flu will peak this year in early December.

CDC Advises Public to Get Flu Vaccine

Because COVID-19 and Influenza have many symptoms in common, such as fever, cough, shortness of breath, fatigue, sore throat, runny nose, headache, and muscle aches, the Mayo Clinic points out on its blog that testing is the only way to discern between the two when symptoms overlap.

According to the CDC, the best way to reduce risk from seasonal flu and its potentially serious complications is to get vaccinated every year. The best time to get vaccinated for the flu is in September and October before the flu starts spreading in communities, the CDC states. However, vaccination after October can still provide protection during the peak of flu season.

Yet, many people fail to get the flu vaccine even though it is recommended for everyone over the age of six months. CNN reported that just 45% of Americans got their flu shots last season. Flu vaccination rates fell for several at-risk groups, including pregnant women and children.

Though flu seasons are often unpredictable, clinical laboratories should prepare now for an influx of influenza test specimens and higher case rates than the past two pandemic-lightened flu seasons. Coupled with COVID-19 and monkeypox testing, already strained supply lines may be disrupted.

—Andrea Downing Peck

Related Information:

Frequently Asked Influenza (Flu) Questions: 2022-2023 Season

Weekly US Influenza Surveillance Report

Australia Just Had a Bad Flu Season. That May Be a Warning for the US

Experts Are Predicting a Bad 2022-2023 Flu Season: How to Prepare Now

Australian Influenza Surveillance Report No 07-Fortnight Ending 03 July 2022

Fauci Warns of a Bad Flu Season Brewing as He Nears Office Exit

Australia’s Tough Flu Season Could Spell Trouble for the US This Winter, Especially with COVID-19 in the Mix

Expect a Different Flu Season: Why You’ll Want to Be Vaccinated for Flu

Influenza Activity and Composition of the 2022–23 Influenza Vaccine—United States, 2021–22 Season

Prevent Seasonal Flu

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