Summer may not be that far gone, but the annual fall and winter respiratory season has already begun.
Flu season typically starts in October, with infection rates peaking in December through February, and then dwindling down by springtime, according to the CDC.
However, CDC data shows flu activity has already begun to rise.
Cases first saw an uptick in the week ending August 8. Since then, flu test positivity has seen a small but sustained increase.
In just the two weeks between September 5 and September 19 – the latest data available – flu test positivity doubled from 1.3 percent to 2.7 percent.
Flu-associated visits to the emergency department have also risen – though they still remain at low levels of 0.3 percent of all ED visits.
Flu activity still remains at the lowest classification of ‘minimal’ in all but four states, but doctors are beginning to observe the early rise in hospitals and at office visits.
Dr Helen Chu, professor of Infectious Diseases at the University of Washington, said the virus has arrived ‘a little bit earlier than we would’ve expected for flu.’
Doctors recommend an annual flu vaccination, which provides protection for six to eight months, to help lower the chances of being infected
The above graph shows the rise in positive flu tests. Cases first saw an uptick in the week ending August 8. Since then, flu test positivity has seen a small but sustained incline
Chu told KUOW: ‘In Seattle and in Washington state, we usually see flu peak in December or January, but this year we’re seeing cases quite early.’
Washington is among four states where levels are slightly above the lowest minimal classification, along with Hawaii, West Virginia and South Carolina.
Typically, experts recommend getting the flu shot by the end of October, but Chu said: ‘I would actually change that this year because of the fact that flu is circulating so early, and recommend that people actually get their flu vaccines now … it is looking like we’re seeing a very, very early surge, and if you get vaccinated now, you can be protected.’
Influenza, commonly known as the flu, is one of the most common and highly contagious respiratory infections, impacting around eight percent of the US population each year.
The infection can cause symptoms such as fever, cough, sore throat, stuffy nose, headaches and fatigue, and can lead to more serious complications including pneumonia and influenza-associated encephalopathy (IAE), a severe brain dysfunction condition.
Doctors recommend an annual flu vaccination, which provides protection for six to eight months, to help lower the chances of being infected.
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.
While most people recover within a week, some may develop complications such as pneumonia, which can be life-threatening and require medical treatment.
The above graph shows the rise in flu-associated outpatient visits. Flu-associated visits to the emergency department have risen – though they still remain at low levels of 0.3 percent of all ED visits
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.
Last year saw a particularly severe flu season as a ‘super flu’ surge was driven by subclade K, a highly mutated variant of the Influenza A (H3N2) virus that caused a rapid and severe spike in cases nationwide.
The strain was brand new to people’s immune systems, making them highly vulnerable and at an increased risk of severe, hospitalizing illness.
The 2025-2026 respiratory season saw at least 32 million flu cases, according to the CDC. There were about 390,000 hospitalizations and 24,000 deaths.
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.
To avoid the flu, 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 or in severe cases, prescription antivirals such as Tamiflu.
