Flu season is off to an unusually fast start this year. Typically in the United States, flu season ramps up in December or January, but reports of the flu are already on the rise in at least 17 states, according to the Centers for Disease Control and Prevention (CDC).
On Nov. 4, federal public health officials said during a press briefing that the U.S. has already “crossed the epidemic threshold” for the flu.
“We are seeing more cases than we would expect at this time,” José Romero, M.D., director of the National Center for Immunization and Respiratory Diseases, told reporters.
Recent online searches show an increase in people wondering if it's normal for the flu to reach epidemic status.
Is it normal for flu seasons to reach epidemic status?
Yes, it is normal for flu seasons to reach epidemic status.
WHAT WE FOUND
Epidemics of seasonal flu happen almost every year, according to the CDC and the World Health Organization (WHO). That’s because the CDC defines an epidemic as “an unexpected increase in the number of disease cases in a specific geographical area” as compared to cases in years past.
Influenza (the flu) is a contagious respiratory illness caused by two types of flu viruses — influenza A and B — that infects the nose, throat, and sometimes the lungs. Flu viruses mainly spread from person to person through droplets made when someone with the flu coughs, sneezes or talks near another person.
“Human influenza A and B viruses cause seasonal epidemics of disease (known as flu season) almost every winter in the United States,” the CDC says on its website.
In an article for medical website Verywell Health, epidemiologist Kristina Duda, RN, also says that “seasonal flu epidemics happen almost every year.”
“Although the word ‘epidemic’ sounds scary, it isn't uncommon for the flu to reach epidemic levels,” Duda said.
To classify flu severity, each week the CDC looks at data from the past five years of flu and pneumonia deaths and makes a baseline. Then they look at this year’s flu and pneumonia death data and if that line hits a certain point over the baseline (for those of you who love math, you can find that baseline formula here), the epidemic threshold has been met. When the percentage of flu deaths drops below the threshold, the epidemic is then considered to be over. The CDC tracks the number of flu-related cases and deaths for each flu season on its website.
During the coronavirus pandemic, the United States saw two mild flu seasons, mostly due to people following certain mitigation methods that can help prevent the spread of respiratory viruses, such as school closures, lockdowns, mask-wearing, and social distancing, that have since ended in most areas of the country. This means the baseline to determine an epidemic is lower than it may have been if the pandemic had never happened.
The best way to prevent the flu is by getting a flu vaccine each year, the CDC says. Other flu prevention methods include:
- Avoid close contact with people who are sick.
- If you are sick, limit contact with others as much as possible to keep from infecting them.
- Cover coughs and sneezes.
- Wash your hands often with soap and water. If soap and water are not available, use an alcohol-based hand rub.
- Avoid touching your eyes, nose, and mouth.
- Clean and disinfect surfaces and objects that may be contaminated with viruses that cause the flu.
The Associated Press contributed to this report.
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