Influenza is typically a self-limiting viral infection that causes symptoms such as fever, chills, cough, rhinitis, headache, sweats, myalgias, and malaise. However, serious illness and complications (eg, pneumonia, death) can occur, particularly in individuals with risk factors. Annual influenza vaccination is recommended for people 6 months and older, including pregnant individuals, who do not have a contraindication to the vaccine. Rapid diagnosis of influenza using point-of-care testing in select patients increases antiviral prescribing and decreases antibiotic prescribing in those with a positive result. However, a negative rapid test result does not exclude influenza. Although most patients do not require treatment for influenza, antivirals should be initiated as soon as possible for patients who are hospitalized, have severe or progressive illness, or are at high risk of complications. Treatment can be considered in symptomatic patients who are household contacts of individuals at high risk of complications or in symptomatic health care professionals who care for patients at risk. Postexposure chemoprophylaxis with antiviral therapies can be considered in individuals who are at risk for influenza complications. Oseltamivir and baloxavir marboxil are commonly recommended antiviral treatment options for influenza. Antiviral treatment is most effective if taken within 24 to 36 hours of symptom onset and reduces symptoms by approximately 20 hours. However, there is little to no evidence that it reduces complications of influenza.
Influenza is typically a self-limiting viral infection; however, serious illness and complications (eg, pneumonia, death) can occur, particularly in individuals with risk factors (Table 1).1,2 The primary mechanism of influenza pathophysiology is lung inflammation and compromise resulting from direct viral infection of the respiratory epithelium and the immune response to the spreading virus. This inflammation can spread systemically and manifest as multiorgan failure; consequences of respiratory failure and multiorgan failure are generally downstream of lung compromise and severe respiratory distress.3
Although influenza viruses do not typically cause serious illness in otherwise healthy individuals, influenza epidemics are associated with significant morbidity and mortality each year worldwide. Influenza A is most common during pandemics because of its higher tendency for antigenic shift. A Centers for Disease Control and Prevention (CDC) analysis of the disease burden in the United States during the 2025–2026 influenza season estimated that influenza accounted for 32 million to 57 million illnesses; 15 million to 25 million medical visits; 390,000 to 800,000 hospitalizations; and 24,000 to 81,000 deaths.4
The 2024–2025 season was the most severe influenza season since 2017–2018 and had the highest number of influenza-associated deaths in children (n = 280) since surveillance in children began in 2004.5,6 Nearly 90% of these deaths occurred in children who were not fully vaccinated.5
WHAT’S NEW ON THIS TOPIC
| The FDA recently approved a messenger RNA–based influenza vaccine (mFlusiva) for adults 50 years and older. |
| The 2024–2025 season had the highest number of influenza-associated deaths in children (n = 280) since surveillance in children began in 2004. Nearly 90% of these deaths occurred in children who were not fully vaccinated. |
| ACIP recommends only single-dose influenza vaccine formulations free of thimerosal. This differs from the AAFP, AAP, and ACOG, which recommend use of any age-appropriate, licensed vaccine. |
AAFP = American Academy of Family Physicians; AAP = American Academy of Pediatrics; ACIP = Advisory Committee on Immunization Practices; ACOG = American College of Obstetricians and Gynecologists; FDA = US Food and Drug Administration.
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