With summer trips ending, students returning to classrooms and cooler weather approaching, Americans are settling back into familiar fall routines.
Health experts say one important item should be added to that autumn checklist: getting an annual flu shot.
The previous US respiratory season was marked by a “super flu” wave fueled by subclade K, a heavily mutated form of the Influenza A (H3N2) virus that triggered a swift and severe rise in cases across the country.
During the 2025-2026 respiratory season, there were at least 32 million flu illnesses, according to the Centers for Disease Control and Prevention (CDC). The virus was also linked to roughly 390,000 hospitalizations and 24,000 deaths.
Influenza, better known as the flu, is among the nation’s most widespread and contagious respiratory illnesses, affecting about eight percent of Americans annually.
It can bring on body aches, headaches, fever and coughing. In some cases, however, the infection can progress to serious complications, including pneumonia and influenza-associated encephalopathy (IAE), a severe condition involving brain dysfunction.
Doctors advise receiving a flu vaccine every year to reduce the risk of infection. But with flu season approaching, the question is when it begins — and whether it is possible to get vaccinated too soon.
According to the CDC, flu season typically starts in October, reaches its highest levels from December through February and declines by spring. As of September 5, flu activity remained minimal across the US.
Doctors recommend an annual flu vaccination to help lower the chances of being infected
Because the vaccine generally offers protection for around six to eight months, experts say the timing of a shot is important. Vaccination too early could mean that protection fades before the flu season has finished.
While pharmacies start stocking the vaccine in August and promoting it in September, doctors agree these months are still too early to get the shot.
October is the ideal month to get vaccinated, with the CDC recommending vaccination by Halloween for the upcoming 2026-2027 respiratory season.
‘October is when I recommend getting the vaccine as there is more actual influenza activity then – there is very little now,’ Infectious disease expert Dr Amesh Adalja, told Prevention.com.
‘The vaccine will last further into the season if administered in October,’ Adalja added.
One exception for an early flu shot is children under eight years old who have never received one – as they would need two doses spaced apart to build immunity.
Additionally, people at high risk of flu complications, such as those with asthma, may want to consider getting vaccinated earlier.
There are three different flu virus strains that cause illness: influenza types A, B and C.
Influenza type A can infect people and animals, while type B is usually found only in humans and is generally associated with less severe infections.
Type C occurs much less frequently than A and B and causes minor illness in humans.
The seasonal flu shot, which is updated every year as the virus mutates, protects against influenza types A and B, as these are the most common and severe strains.
Symptoms of the flu include fever, cough, sore throat, stuffy nose, headaches and fatigue. While most people recover within a week, some may develop complications such as pneumonia, which can be life-threatening and require medical treatment.
The flu shot is one of the most effective preventative measures against infection, reducing the risk of doctor visits by 34 percent and the risk of hospitalization by 30 percent per the CDC, but it can take up to two weeks for the body to develop antibodies after receiving the vaccination.
Because of this, doctors recommend getting the shot a few weeks before an event or gathering where large numbers of people will be indoors.
As of September 5, the US is facing a minimal activity level of flu cases
Anyone can catch the flu, but those most susceptible include people 65 years and older, those with chronic medical conditions, pregnant women, and children under five.
Last year’s dominant strain, dubbed the ‘super flu,’ was brand new to people’s immune systems, making them highly vulnerable and at an increased risk of severe, hospitalizing illness.
While symptoms were the same as other flu strains, experts warned the ‘super flu’ variant was causing more severe illness, especially in children, with signs including week-long fevers and a cough that led to trouble breathing.
Super flu’s symptoms appear to be similar to previous influenza A strains, though doctors have noted they could be more severe.
Health officials recommend regular handwashing and avoiding contact with people who have flu-like symptoms.
Treatment includes rest, staying hydrated, taking over the counter medication such as Mucinex, or in severe cases, prescription antivirals such as Tamilflu.