Flu Activity Is Starting Earlier Across the United States
Flu season is getting an early start in parts of the United States. Signs of influenza began appearing while summer temperatures were still high, weeks before the illness usually spreads widely.
Health experts normally expect flu activity to rise in late fall and reach its highest point during winter. This year, however, testing from laboratories, hospitals, and wastewater systems has shown signs of an earlier increase.
Flu Activity Is Rising in Every State
Flu infections began increasing in early fall, reaching levels that are more common later in the season. Wastewater testing showed higher amounts of flu virus in communities across the country.
All 50 states showed signs of rising flu activity. The strongest activity was seen in western states, including:
- Arizona
- California
- Hawaii
- Nevada
- Alaska
- Idaho
- Oregon
- Washington
National wastewater readings were still considered very low in one federal tracking system. Updates from that system faced a short pause because of a new testing contract, and the length of the pause was not clear.
During one week of testing, about 3.6% of nearly 39,300 flu tests came back positive. That added up to 1,435 positive tests. About 97% of those cases were caused by influenza A. Hospital stays linked to the flu were still low at that point.
A separate wastewater tracking system found that flu activity was high across the nation. This rating means the virus was found in larger amounts in wastewater from more communities.
The wastewater results also pointed to the earliest start of flu activity in at least four years. About 60% of samples tested positive for influenza A during the month, compared with about 20% during the same month the previous year.
Influenza A Is the Main Strain
Influenza A is currently the most common type of flu spreading in the country. It often causes the symptoms people connect with the flu, such as fever, coughing, a runny nose, and body aches.
Influenza B also spreads during flu season, but it usually causes fewer cases than influenza A.
The most commonly detected group of influenza A is A(H1N1)pdm09. This virus was linked to the swine flu pandemic in 2009, when it was new. It is now a regular part of seasonal flu circulation.
Influenza A changes more quickly than other types of flu. It has many subtypes and can lead to outbreaks and large groups of illnesses. These changes are one reason flu vaccines are updated each season to better match the strains expected to spread.
A newly changed influenza A group caused concern during the previous flu season because it helped drive infections and was less closely matched by that season's vaccine.
Common Flu Symptoms
Flu symptoms can look like those of a common cold, but they are often stronger and begin more suddenly. Common signs include:
- Fever
- Chills and body aches
- Cough
- Runny or stuffy nose
- Sneezing
- Sore throat
- Headache
- Tiredness
- Loss of appetite
- Upset stomach
Some people may also have vomiting or diarrhea. These stomach symptoms are more common in children than adults.
Simple Steps Can Help Limit the Spread
Washing your hands often remains one of the best ways to reduce the spread of flu. Use soap and warm water, and scrub for at least 20 seconds.
Handwashing is especially important before and after eating, before and after preparing food, after using the bathroom, and after spending time near someone who is sick. People should also wash their hands after touching surfaces that may carry germs.
Other steps that can lower the risk of infection include:
- Stay home when you are sick.
- Avoid sharing food, drinks, utensils, or personal items.
- Consider wearing a mask when sick or during periods of heavy respiratory illness.
- Limit large indoor gatherings when illness is spreading widely.
- Seek medical advice early if flu symptoms appear.
These precautions are also useful against other illnesses that often spread during the colder months, including respiratory syncytial virus, commonly called RSV.
Some People Face a Higher Risk
Flu can cause serious complications, especially in young children, older adults, pregnant people, and those with weakened immune systems. People with health conditions such as obesity or diabetes may also face a greater risk of severe illness.
Possible complications include pneumonia, inflammation of the brain, inflammation of the heart, and Guillain-Barre syndrome, a rare condition that can affect the nerves and muscles.
Flu may begin with symptoms that resemble a cold. A higher fever, sore throat, muscle pain, headache, and stomach problems may point more strongly to influenza. Parents and caregivers should contact a medical professional early if they believe a child or vulnerable adult may have the flu. Early treatment can help prevent serious illness.
Vaccination Remains the Best Protection
Medical groups recommend that nearly everyone age six months and older receive a flu vaccine each year, including pregnant people. Some people with certain medical conditions may need special guidance before vaccination.
Adults can usually receive the vaccine at a local pharmacy. Parents should check with a child's doctor or pharmacy about vaccine rules and availability.
People age 65 and older should receive a higher-dose vaccine when possible because their immune systems may not respond as strongly to a standard dose.
Protection does not begin immediately. It generally takes about two weeks after vaccination for the body to build a strong immune response. Because flu activity has started early, getting vaccinated sooner may be helpful.
Children younger than 9 who have never received a flu vaccine may need two doses. The doses should be given about four weeks apart. Families should speak with a health care professional to confirm the correct schedule.