From the Guidelines
Influenza is distinguished from other viral respiratory illnesses by its specific combination of symptoms, severity, and epidemiological patterns, and the most recent and highest quality study 1 supports the use of rapid PCR panels for detection of respiratory viruses, including influenza. Influenza typically presents with a sudden onset of high fever, severe muscle aches (myalgia), headache, extreme fatigue, dry cough, and sore throat. Unlike the common cold, which develops gradually and primarily affects the upper respiratory tract, influenza causes more systemic symptoms and can lead to more serious complications like pneumonia, especially in vulnerable populations. Some key points to consider when diagnosing and treating influenza include:
- The illness tends to occur in seasonal epidemics and occasional pandemics, with predictable winter peaks in temperate climates.
- Laboratory testing can definitively identify influenza through rapid antigen tests, PCR, or viral culture.
- Treatment options specifically for influenza include antiviral medications like oseltamivir (Tamiflu) 75mg twice daily for 5 days, zanamivir, peramivir, or baloxavir, which are most effective when started within 48 hours of symptom onset, as recommended by the most recent study 1.
- The unique ability of influenza viruses to undergo antigenic shift and drift results in changing viral strains each season, necessitating annual vaccination with updated formulations targeting the most prevalent strains. It's also important to note that some studies, such as 1 and 1, provide information on the prevention and control of influenza, but the most recent and highest quality study 1 provides the most up-to-date guidance on the diagnosis and treatment of influenza. Additionally, other studies, such as 1, 1, and 1, provide information on the diagnosis and treatment of viral pneumonias, but the most recent and highest quality study 1 provides the most relevant information for distinguishing influenza from other viral respiratory illnesses. Overall, the most recent and highest quality study 1 provides the best guidance for diagnosing and treating influenza, and for distinguishing it from other viral respiratory illnesses.
From the Research
Characteristics of Influenza
- Influenza is an acute viral respiratory infection that causes significant morbidity and mortality worldwide 2
- Three types of influenza cause disease in humans, with Influenza A being the type most responsible for causing pandemics due to its high susceptibility to antigenic variation 2
- The hallmark of infection is abrupt onset of fever, cough, chills or sweats, myalgias, and malaise 2
Diagnosis and Treatment
- For most patients in the outpatient setting, the diagnosis is made clinically, and laboratory confirmation is not necessary 2
- Laboratory testing may be useful in hospitalized patients with suspected influenza and in patients for whom a confirmed diagnosis will change treatment decisions 2
- Rapid molecular assays are the preferred diagnostic tests because they can be done at the point of care, are highly accurate, and have fast results 2
- Treatment with one of four approved anti-influenza drugs may be considered if the patient presents within 48 hours of symptom onset 2
- The benefit of treatment is greatest when antiviral therapy is started within 24 hours of symptom onset 2, 3, 4, 5
Comparison of Anti-Influenza Drugs
- Zanamivir and oseltamivir are two new options for the treatment and prevention of influenza, and are effective against both influenza A and influenza B 3, 4
- These drugs decrease the duration of illness by about 1 day if initiated within 48 hours of the onset of symptoms of influenza 4
- The efficacy and safety of oseltamivir and zanamivir are similar, but temperature normalization was significantly faster in patients taking zanamivir 6
- Patients using zanamivir should be monitored for respiratory distress 6