Influenza is primarily a community-based infection that is transmitted in households and community settings. Each year, 5% to 20% of U.S. residents acquire an influenza virus infection, and many will seek medical care in ambulatory healthcare settings (e.g., pediatricians’ offices, urgent-care clinics). In addition, more than 200,000 persons, on average, are hospitalized each year for influenza-related complications. Healthcare-associated influenza infections can occur in any healthcare setting and are most common when influenza is also circulating in the community. Therefore, the influenza prevention measures outlined in this guidance should be implemented in all healthcare settings. Supplemental measures may need to be implemented during influenza season if outbreaks of healthcare-associated influenza occur within certain facilities, such as long-term care facilities and hospitals [refs: Infection Control Measures for Preventing and Controlling Influenza Transmission in Long-Term Care Facilities].

Influenza Modes of Transmission

Traditionally, influenza viruses have been thought to spread from person to person primarily through large-particle respiratory droplet transmission (e.g., when an infected person coughs or sneezes near a susceptible person). Transmission via large-particle droplets requires close contact between source and recipient persons, because droplets generally travel only short distances (approximately 6 feet or less) through the air. Indirect contact transmission via hand transfer of influenza virus from virus-contaminated surfaces or objects to mucosal surfaces of the face (e.g., nose, mouth) may also occur. Airborne transmission via small particle aerosols in the vicinity of the infectious individual may also occur; however, the relative contribution of the different modes of influenza transmission is unclear. Airborne transmission over longer distances, such as from one patient room to another has not been documented and is thought not to occur. All respiratory secretions and bodily fluids, including diarrheal stools, of patients with influenza are considered to be potentially infectious; however, the risk may vary by strain. Detection of influenza virus in blood or stool in influenza infected patients is very uncommon.

Fundamental Elements to Prevent Influenza Transmission

Preventing transmission of influenza virus and other infectious agents within healthcare settings requires a multi-faceted approach. Spread of influenza virus can occur among patients, HCP, and visitors; in addition, HCP may acquire influenza from persons in their household or community. The core prevention strategies include:

• administration of influenza vaccine
• implementation of respiratory hygiene and cough etiquette
• appropriate management of ill HCP
• adherence to infection control precautions for all patient-care activities and aerosol-generating procedures
• implementing environmental and engineering infection control measures.

Successful implementation of many, if not all, of these strategies is dependent on the presence of clear administrative policies and organizational leadership that promote and facilitate adherence to these recommendations among the various people within the healthcare setting, including patients, visitors, and HCP. These administrative measures are included within each recommendation where appropriate. Furthermore, this guidance should be implemented in the context of a comprehensive infection prevention program to prevent transmission of all infectious agents among patients and HCP.

To learn more, please visit https://www.cdc.gov/flu/professionals/infectioncontrol/healthcaresettings.htm.

Getting an annual flu vaccine is the best way to protect yourself and your loved ones from flu.

If you are at higher risk of developing serious flu complications, flu vaccination is especially important. When you get vaccinated, you reduce your risk of getting sick with flu and possibly being hospitalized or dying from flu.

Following is a list of all the health and age factors that are known to increase a person’s risk of getting serious flu complications:

• Adults 65 years and older
• Children younger than 2 years old¹
• Asthma
• Neurologic and neurodevelopment conditions
• Blood disorders (such as sickle cell disease)
• Chronic lung disease (such as chronic obstructive pulmonary disease [COPD] and cystic fibrosis)
• Endocrine disorders (such as diabetes mellitus)
• Heart disease (such as congenital heart disease, congestive heart failure and coronary artery disease)
• Kidney diseases
• Liver disorders
• Metabolic disorders (such as inherited metabolic disorders and mitochondrial disorders)
• People who are obese with a body mass index [BMI] of 40 or higher
• People younger than 19 years old on long-term aspirin- or salicylate-containing medications.
• People with a weakened immune system due to disease (such as people with HIV or AIDS, or some cancers such as leukemia) or medications (such as those receiving chemotherapy or radiation treatment for cancer, or persons with chronic conditions requiring chronic corticosteroids or other drugs that suppress the immune system)
• People who have had a stroke

Other people at higher risk from flu:

• Pregnant people and people up to 2 weeks after the end of pregnancy
• People who live in nursing homes and other long-term care facilities
• People from certain racial and ethnic minority groups are at increased risk for hospitalization with flu, including non-Hispanic Black persons, Hispanic or Latino persons, and American Indian or Alaska Native persons
• ¹ Although all children younger than 5 years old are considered at higher risk of serious flu complications, the highest risk is for those younger than 2 years old, with the highest hospitalization and death rates among infants younger than 6 months old.

Information on groups at higher risk from COVID-19 is available.’

To learn more information, please visit https://www.cdc.gov/flu/highrisk/index.htm.