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Influenza, or flu, is a respiratory infection caused by a variety of flu viruses. The "flu" is a common catch-all term used for a variety of illnesses, but it correctly applies only to the upper respiratory disease caused by the influenza virus.

Estimates are that between 15% and 40% of the population will develop illness from influenza every year. An average of about 36,000 people per year in the United States die from influenza, and 114,000 per year have to be admitted to the hospital as a result of influenza infection. Anyone can get the flu (even healthy people), and serious problems from influenza can happen at any age. People age 65 years and older, people of any age with chronic medical conditions, and very young children are more likely to get complications from influenza.

For the most current information about influenza in Florida, please see Florida's Weekly Surveillance Report, the Florida Flu Review.

Week 19 2015 Florida Flu Review Surveillance Summary

National Influenza activity

  • Influenza activity continues to decrease nationally.
  • The Centers for Disease Control and Prevention (CDC) has identified an antigenically drifted influenza A (H3N2) strain circulating nationally and in Florida that is different from the strain of influenza A (H3N2) contained in the current 2014-15 influenza vaccine formulations.
  • The CDC indicates this season's vaccine offers reduced protection. Individuals at high risk of complications from influenza infection with suspected influenza should be treated with antivirals as early as possible, even prior to laboratory confirmation. For more information read the letter for health care providers.
  • The CDC indicates that antiviral medications are underutilized; one study estimates antivirals were only used one out of five times where antivirals use would be recommended.
  • The overall hospitalization rate for the season (Between October 1, 2014 and April 30, 2015) was 65.4 per 100,000 population. The highest rate of hospitalization was among adults aged ≥65 years (322.2 per 100,000 population), this is the hospitalization rate recorded since data collection on laboratory-confirmed influenza-associated hospitalization in adults began during the 2005-2006 season. Higher morbidity and mortality is expected in years where H3N2 is the predominately circulating strain.

State Influenza and influenza-like illness (ILI) activity

  • Influenza activity continues to decline overall or remain at low levels across the state.
  • This season, influenza and ILI activity started early and peaked in week 52.
  • Seasons like this one, where influenza A (H3) is the predominantly circulating strain, are typically associated with higher morbidity and mortality, particularly in adults ≥65 years old.
  • 75 (71%) of reported outbreaks of ILI have been in facilities primarily serving adults ≥65 years old.
  • Most Florida counties are reporting mild influenza activity. In week 19, 33 counties reported decreasing influenza activity; 33 counties indicated activity is at a plateau.
  • Emergency department (ED) and urgent care center (UCC) ILI visits have decreased in recent weeks and are slightly below levels typical for this time of year. The number of pneumonia and influenza (P&I) associated deaths have declined overall in recent weeks and are above levels seen in previous years at this time.
  • In Florida, the most common influenza subtype detected at the Bureau of Public Health Laboratories (BPHL) in recent weeks has been influenza B although influenza A (H3) has been the predominantly circulating strain for the majority of the season. The increase in influenza B late in the season follows previous yearly trends.
  • In the past week, three (23.1%) of 13 specimens submitted to BPHL for influenza testing were PCR positive for seasonal strains of influenza: one was positive for influenza B Yamagata lineage, and two were influenza B not yet subtyped.
  • No outbreaks of influenza-like illness (two or more cases of influenza or ILI in a specific setting) were reported to EpiCom in week 19.
  • No pediatric influenza-associated deaths were reported in week 19.

For more information about Avian Influenza (H7N9), please click here: Avian Influenza (Bird Flu)

New! Long-Term Care Facility Administrators Letter
New! Long-Term Care Faciltiy Administrators Guidance
New! 2014-15 Letter and Guidance to Physicians(December 5, 2014)

New! Guidance for Health Care Providers (December 5, 2014)
New! Sample Letter To Parents (December 5, 2014)
New! Letter to Schools (December 5, 2014)
Letter to Providers: Influenza Prevention (March 14, 2014)
Letter to Providers: Pregnant Women and Influenza Vaccination Recommendations (December 17, 2013)
Press Release: DOH Reminds Pregnant Woman that Flu Vaccination is Important (December 12, 2013)
Antiviral Usage: Influenza
Influenza Fact Sheet for Home
Influenza General Public Fact Sheet
Florida Influenza Weekly Surveillance (Flu Review)
Florida Influenza-like Illness Surveillance Network
Guidelines for the Flu Lab Report in Merlin
The Flu In the United States (CDC)
Press Release (December 28, 2010)
Respiratory Syncytial Virus (RSV) 
Severe Acute Respiratory Syndrome (SARS)
Information for Directors of Long-Term Care Facilities
Novel Influenza A H1N1 Outbreak: Florida Response Satellite Broadcast
Pandemic Influenza

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