What is influenza?
“Contagious respiratory illness caused by influenza viruses that infect the nose, throat, and lungs”1
History of Influenza5
● Flu pandemic of 1918 to 1919 infected about 500 million people worldwide and killed 20 to 50 million.
● In the U.S., more than 25% of Americans became sick, and 675,000 Americans died.
● Pandemic caused by flu virus that had invaded lungs and caused pneumonia.
● AKA Spanish flu
Clinical Presentation
● Systemic
○ Fever, chills, headache, myalgia,
malaise, anorexia ● Respiratory
○ Cough, severe pharyngeal pain, nasal obstruction and discharge
● Complications
○ Viral pneumonia, secondary bacterial
pneumonia
urgentcareatlanta.com
Influenza Virus
● Family
○ Orthomyxoviridae
● Type of Nucleic Acid
○ 6-8 SS (-) RNA segments
● Genome Size ○ 10-15 kb
micro.magnet.fsu.edu
Influenza Viruses
● Classification
○ Influenza A, B, C
● Epidemiology
○ U.S. mortality can be as high as 51,000
● Pathogenesis
○ Respiratory droplets and aerosols
○ Presentation of symptoms in 1-2 days
● Diagnosis
○ Nose and throat swab specimens
○ Viral antigen detection
○ Serologic tests
techtreme.com
Classification
● Influenza A
○ Humans, birds, pigs, horses, marine mammals
○ Divided according to hemagglutinin and neuraminidase subtype
● Influenza B
○ Humans only
○ Not classified to subtype
● Influenza C
○ Humans only; mild illness
○ Not classified to subtype
Anti-Influenza Agents- Neuraminidase Inhibitors
Drugs
MOA
Other Info
● oseltamivir (Tamiflu) (PO)
● zanamivir (Relenza) (inhalation)
● peramivir (Rapivab) (IV)
Competitively and reversibly interacts with the active enzyme (sialic acid) to inhibit viral neuraminidase activity
● Vast majority of circulating viruses are susceptible to these agents
● Oseltamivir or zanamivir = for
patients with confirmed or suspect influenza who have severe, complicated, or progressive illness
Anti-Influenza Agents- M2 Inhibitors
Drugs
MOA
Other Info
● amantadine (Symmetrel) (PO)
● rimantadine (Flumadine) (PO)
block the M2 proton ion channel of the virus particle and inhibits uncoating of the viral RNA within infected host cells, which prevents replication
● Not recommended for treatment or
prophylaxis of influenza A due to resistance
● Not effective against influenza B
Treatment of Influenza2
● Subset of patients with confirmed or suspected influenza who require treatment
within 24 hours – 48 hours MAX ○ Hospitalized
○ Severe, complicated, or progressive illness (e.g., post-flu pneumonia)
○ Patients at higher risk for influenza complications
■ Children < 2 years or adults > 65 years
■ Those with chronic pulmonary, CV, renal hepatic, hematological, metabolic, or neurologic
disorders, stroke, or intellectual disability
■ Immunosuppressed
■ Pregnant or postpartum
■ Morbidly obese
■ Residents of nursing homes or other chronic-care facilities
■ American Indians/Alaska Natives
Treatment Recommendations3
● oseltamivir (Tamiflu)
○ Influenza A and B; oral only
○ Treatment: Any age
○ Chemoprophylaxis: 3 months and older
○ AEs:
■ Nausea, vomiting, serious skin reactions and sporadic, transient neuropsychiatric events (self-injury or delirium); mainly reported among Japanese adolescents and adults)
● peramivir (Rapivab)
○ Influenza A and B; IV only
○ Treatment: 18 years and older
○ Chemoprophylaxis: N/A
○ AEs:
■ Diarrhea, postmarketing reports of serious skin reactions and sporadic, transient neuropsychiatric events (self-injury or delirium; mainly reported among Japanese adolescents and adults)
natcopharma.co.in
Treatment Recommendations3
● zanamivir (Relenza)
○ Influenza A and B; inhalation only
○ Treatment: 7 years and older
○ Chemoprophylaxis: 5 years and older
○ Not recommended for use in people with underlying
respiratory diseases (e.g., asthma, COPD)
○ AEs
■ Diarrhea, nausea, sinusitis, nasal signs and symptoms, bronchitis, cough, headache, dizziness, and ear, nose and throat infections
drugs.com
Prevention1,2
● Stay away from sick people
● Stay home if you’re sick
● Cover coughs and sneezes
● Avoid touching your eyes, nose, or mouth
● Proper hand washing techniques
● Receive annual flu vaccination
http://www.health.state.mn.us
Prevention – Vaccinations1,2
Inactivated
● Trivalent
○ Virus grown in eggs (ask about egg
allergy before administration)
○ > 65 y/o: high-dose
● Quadrivalent
○ Virus grown in cell culture
Live-Attenuated
● FluMist
● Administered intranasally
● Not approved for 2016-2017 season
Fast Facts2
● How does the vaccine work?
○ Antibodies develop in the body 2 weeks after
administration
○ These antibodies provide protection against the
viruses in the vaccine
● Who should get vaccinated?
○ Everyone 6 months of age and older ● When is flu season?
○ October – May
● Why get the vaccine every year?
○ Flu viruses are always changing
● Does the flu vaccine cause the flu? ○ NO!
blogs.scientificamerican.com
2016-2017 Flu Season
● Three-component vaccines are recommended to contain:
○ A/California/7/2009 (H1N1)pdm09-like virus
○ A/Hong Kong/4801/2014 (H3N2)-like virus and a
○ B/Brisbane/60/2008-like virus (B/Victoria lineage).
● Four component vaccines = the same three viruses above + additional B virus called B/Phuket/3073/2013-like virus (B/Yamagata lineage)
● Live attenuated influenza vaccine or nasal spray are not recommended for use during 2016-2017 season because of concerns about its effectiveness
4
4
4
2016-2017 Flu Season Synopsis4
● Most frequently identified influenza virus subtype reported was influenza A (H3).
● Proportion of deaths caused by pneumonia and influenza was reported to be above epidemic threshold.
● Five pediatric deaths caused by influenza.
● 46.9 hospitalizations per 100,000 caused by influenza.
● Outpatient visits for influenza-like illness was 3.7% (above national
baseline of 2.2%).
● 36 states reported influenza as widespread.