With summer holidays winding down, schools reopening and cooler weather on the way, Americans are gradually returning to their familiar fall routines.
Health experts say that annual flu vaccination should be added to the seasonal checklist.
The previous respiratory season brought a major “super flu” wave to the US. Much of the surge was linked to subclade K, a heavily mutated form of the Influenza A (H3N2) virus that fueled a sharp rise in infections across the country.
During the 2025-2026 respiratory season, the US recorded at least 32 million flu cases, according to the Centers for Disease Control and Prevention (CDC). The outbreak also led to approximately 390,000 hospitalizations and 24,000 deaths.
Influenza, better known as the flu, is among the most widespread and contagious respiratory illnesses, affecting roughly 8 percent of the US population in a typical year.
Common symptoms include fever, coughing, headaches and muscle aches. In some cases, however, influenza can develop into potentially serious complications such as pneumonia or influenza-associated encephalopathy (IAE), a condition involving severe brain dysfunction.
An annual flu vaccine can reduce the risk of infection, but many people still wonder when flu season officially begins—and whether getting vaccinated too soon could limit its protection.
According to the CDC, flu activity generally begins to increase in October, reaches its highest levels between December and February, and declines during the spring. As of September 5, influenza activity in the US remained minimal.
Doctors advise getting a flu vaccine every year to help reduce the risk of infection
Flu vaccination typically offers protection for around six to eight months, making the timing of the shot important. Receiving it too early may allow immunity to weaken before the season is over.
Although pharmacies often begin receiving flu vaccines in August and advertising them in September, physicians say those dates are generally earlier than necessary for most people.
October is widely considered the best time to get vaccinated. For the 2026-2027 respiratory season, the CDC advises people to receive their flu shot by Halloween.
“October is when I recommend getting the vaccine, as there is more actual influenza activity then—there is very little now,” infectious disease specialist Dr. Amesh Adalja told Prevention.com.
“The vaccine will last further into the season if administered in October,” Adalja added.
There is one important exception: children younger than eight who have never had a flu vaccine may need an earlier start. They typically require two doses, given several weeks apart, to develop 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.
