Influenza Flashcards
What is one of the most common causes of respiratory infections?
influenza
What is the significance of influenza?
it causes high rates of morbidity and mortality
What are the most common causes of influenza like illness (ILI)?
Influenza A and B
Aside from Influenza A and B, what are other causes ILI?
influenza C
parainfluenza virus
RSV
mycoplasma pneumoniae
How is influenza spread?
inhalation of droplets (coughing, sneezing)
direct or indirect contact with contaminated resp secretions
What is the incubation period of influenza?
1.5-2 days (range 1-4)
How long can an adult influenza-sufferer spread influenza?
one day before symptoms to approx 5 days after onset
Which group of people might be infectious longer with influenza?
children
immunocompromised
What is the “normal” season for influenza?
november-april
peaks in winter months
Describe the biology of influenza.
negative strand RNA virus covered with protective envelope
each RNA segment is encapsulated by nucleoproteins which forms a ribonucleotide-nucleoprotein complex (RNP)
What covers the lipid envelope of influenza?
haemagglutinin (HA)
neuraminidase (NA)
matrix 2 (M2) ion channels
What is the antigenic portion of influenza?
HA
NA
M2 ion channels
Describe the steps in the invasion and replication of influenza?
- HA initiates infection by binding to host cell within resp tract
-endocytosis brings virus into cell - vRNA + other things are released into cytoplasm
-then transported to nucleus - complementary (+) sense vRNA is transcribed, and may
be exported into the cytoplasm to get translated or stay
in nucleus - new viral proteins (HA, NA, etc) are secrted through GA onto
cell surface or may be transported back to the nucleus to
form new viral genome particles - vRNA and proteins leave nucleus and bulge out of host
membrane that is coated in viral surface proteins - mature virus buds off from cell
What happens to a host cell after a new virus is released?
the cell dies
What is influenza antigenic shift/drift?
appearance of influenza (usually A) with new HA or NA subtypes
What is the impact of influenza antigenic shift on our immunity to influenza?
variations within a subgroup may be so different that immunity to one related strain may not mean immunity to others
immunity to one subtype does not protect against other subtypes
Why are influenza vaccines reformulated every year?
antigenic shift
-based on changing patterns of the virus
What causes influenza antigenic shift?
mutations during replication
-the virus has no proof reading
True or false: nearly every newly-manufactured influenza virus is a mutant
true
What is cited as being the most devastating epidemic ever?
influenza pandemic of 1918-19
-infected 20% of the world population
-mortality rate of 2.5-20%
-most deadly for people ages 20-40
-killed up to 50 million
Which pandemic occurred in 2009?
H1N1 pandemic
-the latest influenza pandemic
-began in mid April 2009, peaked in first 3 weeks of June
What are the signs and symptoms of influenza?
sudden onset of:
-high fever (usually chills first): lasts 7-10 days
-cough (may persist for 2 weeks)
-sore throat
-myalgias and fatigue (can be severe and may linger for
weeks)
-headache, loss of appetite, coryza, N, V, D (esp kids)
How long does it take most people to recover from influenza?
7-10 days
What kind of infection is influenza?
acute respiratory tract infection
-NOT GI INFECTION
What are the respiratory complications of influenza?
pneumonia (most common)
-could be viral or secondary bacterial penumonia
excacerbation of chronic lung disease
croup or bronchiolitis (in young kids)
otitis media
What are the respiratory complications of influenza?
pneumonia (most common)
-could be viral or secondary bacterial penumonia
exacerbation of chronic lung disease
croup or bronchiolitis (in young kids)
otitis media
What are the non-respiratory complications of influenza?
excacerbation of underlying conditions:
-febrile seizures
-Reye syndrome
-encephalitis
-Guille Barre syndrome
-myositis
-myocarditis
Who is at higher risk of complications from influenza?
patients with:
-heart disease
-lung disease
-diabetes
-renal disease
-rheumatologic disease
-dementia
-stroke
pregnant women
extremes of age
immunosuppressed
What is the best way to prevent influenza?
vaccine
What is Reye syndromes?
accumulations of fat develop in liver and other organs, along with severe increase of pressure in the brain
What is Guille Barre syndrome?
autoimmune attack on the peripheral nervous system
What is influenza vaccine formulation based on?
HA and NA of each virus subtype that are most common
Which strains of influenza does WHO recommend be in the trivalent vaccine?
influenza A (H1N1)
influenza A (H3N2)
influenza B
Which strains of influenza does WHO recommend be in the quadrivalent vaccine?
same as trivalent as well as an influenza B from the lineage that is not included in the trivalent vaccine
Define the following: IIV3, IIV4, LAIV3, LAIV4, IIV3/4-SD, IIV3-Adj, IIV3-HD, IIV4-HD, IIV4-cc, RIV4
IIV3: inactivated influenza vaccine trivalent
IIV4: inactivated influenza vaccine quadrivalent
LAIV3: live attenuated influenza vaccine trivalent
LAIV4: live attenuated influenza vaccine quadrivalent
IIV3/4-SD: standard dose, unadjuvanted; IM administration
IIV3-Adj: adjuvanted; IM administration
IIV3-HD: high dose, unadjuvanted; IM administration
IIV4-HD: high dose, unadjuvanted; IM administration
IIV4-cc: SD, unadjuvanted, IM administration, cell culture-based
RIV4: recombinant protein; IM administration
What is the composition of the quadrivalent influenza vaccine for 2022-23 season?
egg-based vaccine composition
H1N1 (A)
H3N2 (A)
Victoria (B)
Yamagata (B)
Which influenza vaccines are indicated in Saskatchewan?
IIV4-SD
IIV4-HD
What is the dose and route of administration of IIV4-SD?
15ug HA/0.5mL dose
IM
What is the dose and route of administration of IIV4-HD?
50ug HA/0.7mL dose
IM
Which age group is indicated to receive the IIV4-HD?
65 years and older