December 7-13, 2014 is National Influenza Vaccination Week (NIVW), the time when public health authorities in the United States collaborate to spread the word about the importance of flu vaccination.
The Centers for Disease Control and Prevention (CDC) started off NIVW in 2005. The aim is to remind the public that vaccination can provide protection against flu viruses and that vaccination should continue during and after the holiday season. Flu vaccine can offer protection against three or four different seasonal flu viruses. The CDC recommends that everyone 6 months of age and older gets a yearly flu vaccine to protect against influenza disease. NIVW also stresses the importance of flu vaccination for people who are at high risk for developing flu-related complications.
Clinical laboratories have an important role to play during the flu season as proper treatment of patients with respiratory issues depends on accurate and timely diagnosis. Diagnostic testing with viral culture, serology, rapid antigen testing, polymerase chain reaction (PCR), or highly sensitive and specific enzyme immunoassays is crucial as clinical diagnosis of influenza based on symptoms alone cannot be trusted since symptoms from illness caused by other pathogens can have characteristics common to influenza. Moreover, influenza can lead to complications such as bacterial infections.
CDC and WHO have recommended strategies for influenza diagnostic testing for inpatients and outpatients. The FDA points out that while rapid tests provide preliminary tools for guiding treatment and patient management, and can be useful to determine if influenza is the cause of an outbreak of a respiratory illness in a particular setting, laboratorians and clinicians should interpret the results from a rapid influenza test in the light of:
- Clinical experience
- Further laboratory testing
- Surveillance information about circulating influenza strains and the level of influenza activity
- An understanding of the limitations of the rapid tests
- Published literature
The FDA cautions that clinicians and laboratorians assessing the qualities of individual tests should know that test sensitivities and specificities may differ across patient groups, levels of influenza activity, at different times after onset of symptoms, with different specimen types, and under different lab conditions. Proper specimen collection, storage, and transport are also critical to avoid false negative tests.
This NIVW week, we join the health authorities in reminding the public that getting the flu vaccine is the best defense against seasonal influenza. We also remind clinical laboratories to ensure preparedness with accurate and timely diagnostic tests and reagents.