Influenza

Influenza (flu) is a contagious respiratory illness caused by viruses that infect the nose, throat, and lungs. Some people are at higher risk of serious complications due to influenza. There are two main types of influenza viruses: Types A and B. The influenza A and B viruses that routinely spread in people (human influenza viruses) are responsible for seasonal epidemics each year.

Click here to view 2024-2025 Flu Season Weekly Surveillance Reports

Flu Symptoms:

Flu can cause mild to severe illness and can sometimes lead to death. Flu symptoms usually start from one to four days after infection with the flu virus. A person's symptoms can start suddenly. People who have flu often feel some or all of these symptoms:

  • Coughing into elbow

    Cough

  • Headache

    Headache

  • Sore throat

    Sore throat

  • Person with thermometer in mouth

    Fever or Chills

  • Nose dripping

    Congestion or runny nose

  • Leg pain

    Muscle or body aches

People with flu may also experience fatigue (feeling very tired). Some people may have vomiting and diarrhea, but this is more common in children than adults.

Information For:

General Public

Schools

  • Preventing and Responding to Flu
    • Schools should report when they reach >= 15% absenteeism due to illness. Reporting should occur through NEO.
    • Encourage students, parents, and staff to get their annual flu shot.
    • Students and staff with flu-like illness should stay home. They can return at least 24 hours after they no longer have a fever without the use of fever-reducing medication. Children who come to school experiencing flu-like symptoms should be sent home.
    • Encourage students, parents, and staff to take basic preventive actions. This includes covering their coughs and washing their hands.
    • School administrators with questions about flu or reporting >= 15% absenteeism should contact Maine CDC at 1-800-821-5821 or disease.reporting@maine.gov.
  • Additional Resources:

Long-Term Care Facilities

Childcare Providers

  • Remind children and care providers to practice good hand hygiene.
    • Encourage the use of soap and water, or an alcohol-based hand cleaner to wash hands.
    • Encourage care providers to wash their hands to the extent possible between contact with infants and children. This includes:
      • Before meals or feedings,
      • After wiping a child's nose or mouth,
      • After touching tissues or other objects soiled with saliva or nose drainage,
      • After diaper changes, and
      • After assisting a child with toileting.
    • Encourage children to wash hands when their hands have become soiled. Teach children to wash hands for at least 20 seconds (long enough to sing the "Happy Birthday" song twice).
    • Oversee the use of alcohol-based hand cleaner. Avoid using these on the sensitive skin of infants and toddlers. Keep alcohol-based hand cleaner out of the reach of children.
    • Ensure that sink locations and restrooms are stocked with soap, paper towels, and working hand dryers.
  • Keep the care environment clean and make sure that cleaning supplies are available for employee use.
    • Clean frequently touched surfaces, toys, and commonly shared items. Keep disinfectants out of the reach of children.
    • Use an Environmental Protection Agency (EPA)-registered household disinfectant labeled for activity against bacteria and viruses, an EPA-registered hospital disinfectant, or EPA-registered chlorine bleach/hypochlorite solution. If EPA-registered chlorine bleach is not available and a generic (i.e., store brand) chlorine bleach is used, mix 1/4 cup of chlorine bleach with 1 gallon of cool water.
  • Remind children and care providers to cover their sneezes and coughs.
    • Remind children and care providers to put their used tissues in the trash.
    • Children and providers to wash their hands or use hand sanitizer after sneezing or coughing.
  • Observe infants and children for symptoms of respiratory illness. Notify the parent if a child develops a fever or chills, cough, sore throat, headache, or muscle aches. If possible, send the child home and tell the parent to contact the child's doctor.
    • If a child has difficulty breathing, is lethargic, or appears to be worsening, call a physician or 911.
  • Encourage sick children and sick employees to stay home. Employees or children who are sick should stay home until they have been fever free for 24 hours.
  • Additional Resources:

Businesses or Employers

  • Keeping Healthy: Tips for Businesses
    1. Develop policies that encourage symptomatic workers to stay home.
    2. Develop other flexible policies to allow workers to telework if possible. Create other leave policies to allow workers to stay home to care for sick family members.
    3. Provide resources and a work environment that promotes personal hygiene. Provide tissues, hand soap, hand sanitizer, disinfectants, and disposable towels.
    4. Instruct employees who are well but who have an ill family member that they can go to work as usual. These employees should monitor themselves for symptoms.
    5. Encourage employees to get a seasonal flu vaccine.
    6. Provide employees with information on risk factors, protective behaviors, and instruction on hygiene.
    7. Plan to include practices to reduce face-to-face contact if advised by Maine CDC. Consider the use of e-mail, teleconferences, and flexible work arrangements. This may reduce the number of people who must be at the work site at the same time or in one specific location.
    8. If an employee does become sick while at work, the employee should go home immediately.
  • Additional Resources:

Young Children, Older Adults, and People With Certain Health Conditions

    Young Children

    • Children younger than 5 years old are at higher risk of flu-related complications. Each year, millions of children get sick with seasonal flu and thousands are hospitalized. Children sometimes need medical care because of flu. For more information, visit US CDC's website: Flu & Young Children.

    Older Adults

    • People 65 years and older are at a higher risk of developing serious flu complications. This increased risk is due in part to changes in immune defenses with increasing age. During most seasons, people 65 years and older bear the greatest burden of severe flu disease. It's estimated that between 70 and 85 percent of seasonal flu-related deaths have occurred in people 65 years and older, and between 50 and 70 percent of seasonal flu-related hospitalizations have occurred among people in this age group. For more information, visit US CDC's website: Flu & People 65 Years and Older.

    Pregnant Women

    • Flu is more likely to cause severe illness in pregnant people than in people of reproductive age who are not pregnant. Changes to the immune system, heart, and lungs during pregnancy make people more susceptible to illness severe enough to cause hospitalization throughout pregnancy and up to two weeks postpartum. Influenza may also be harmful for the developing baby. A common flu symptom, fever, may be associated with neural tube defects and other adverse outcomes for a developing baby. For more information, visit US CDC's website: Flu & Pregnancy.

    People with Certain Health Conditions

    • People with asthma, heart disease, diabetes, HIV/AIDS, cancer, and other chronic health conditions are at higher risk of flu complications. In fact, 9 out of 10 people hospitalized with flu had at least one underlying condition. For more information, visit US CDC's website: Flu & People at Increased Risk for Flu Complications.

     

Healthcare Workers and Healthcare Providers

Healthcare Workers

  • Healthcare workers (HCW) are personnel who work in acute care hospitals, nursing homes, skilled nursing facilities, physician offices, urgent care centers, outpatient clinics, and home healthcare agencies. Those working in clinical settings within non-healthcare institutions, such as school nurses or those staffing clinics in correctional facilities are also considered HCWs.
  • HCWs include all people whose occupational activities involve contact with patients or contaminated materials in healthcare settings, including home healthcare or clinical laboratory settings. This includes those who do not provide direct patient care, but have patient contact, such as personnel involved in dietary and housekeeping services. HCWs include all contractors, clinicians, volunteers, students, trainees, clergy, and others who come in contact with patients.
  • Even if you're healthy, you can get sick and spread flu. Get vaccinated to help protect yourself from flu and to keep from spreading it to your family, co-workers, and patients. You should get the seasonal flu vaccine every year because flu viruses change yearly and a flu vaccine from a previous season may not protect against current flu viruses.

Healthcare Providers

  • Clinicians should consider flu in the differential diagnosis of febrile respiratory illness in patients of any age. Encourage all patients, especially high-risk patients to be immunized against flu if they have not already done so. Review updated recommendations on the use of antiviral medications for prophylaxis and treatment.
    • Oseltamivir phosphate (available as generic version or under the trade name Tamiflu®), zanamivir (trade name Relenza®), and peramivir (trade name Rapivab®) are drugs currently available as treatment and prophylaxis and baloxavir marboxil (trade name Xofluza®) as treatment only. Providers will be notified through the Health Alert Network (HAN) if national recommendations for treatment and prophylaxis are revised.
  • Laboratories should send up to three (3) influenza A and one (1) influenza B positive specimens to Maine's Health and Environmental Testing Laboratory (HETL) each week for confirmatory polymerase chain reaction (PCR) testing and further analysis. Testing through HETL is free of charge.
  • Infection preventionists, clinicians, school nurses, and other reporting entities must report all suspected outbreaks of flu to Maine CDC by phone at 1-800-821-5821 or email disease.reporting@maine.gov.
  • Maine CDC and US CDC recommend all individuals older than 6 months to be immunized, even if they were vaccinated for flu last year. All individuals with high-risk conditions should be vaccinated as soon as possible.
  • US CDC's Influenza Information for Health Professionals.

Vaccines

Start of Season Conference Call:

Maine CDC: Pandemic Influenza Operations Plan (PIOP)

PIOP

  • To view Maine CDC's Pandemic Influenza Operations Plan and Functional Annexes, click here.

Influenza Reporting

For facilities and institutions required to report diseases and conditions (see Maine's Rules for the Control of Notifiable Conditions), the following must be reported to Maine CDC:

  • Influenza-associated hospitalizations
  • Influenze-associated deaths in children less than 18 years old
  • Influenza and influenza-like illness outbreaks, defined in the table below.
Influenza Outbreak Definitions for Facility Types
Facility Type Outbreak Definition
Long-Term Care 2 or more residents are ill with influenza-like illness, or laboratory confirmed influenza, within 72 hours of each other
Acute Care One or more patients with laboratory-confirmed influenza with symptom onset greater than 48 hours post admission
K-12 Schools Greater than or equal to 15% absenteeism among students in a single day where the majority of those absent report respiratory symptoms

All other institutions, including childcare facilities and higher education institutions, should report when experiencing higher than expected number of influenza cases. Note: For childcare facilities within K-12 schools that include child attendance in school absenteeism, the childcare facility does not need to report separately.

Questions about influenza?

Call Maine CDC at 1-800-821-5821 or send an email to influenza.dhhs@maine.gov.

Sign-up to receive weekly Maine CDC influenza surveillance reports.