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
What is the dose and route of administration of IIV4-cc?
15ug HA/0.5mL dose
IM
What is the dose and route of administration of RIV4?
45ug/0.5mL dose
IM
What is the age restriction of RIV4?
18 years and older
What is the dose and route of administration of LAIV4?
10 to the 6.5-7.5 FFU/0.2ml as 0.1ml
nostril
What is the age restriction on LAIV4?
2-59 years
Why are adjuvants added to vaccines?
to increase the immune response to vaccine
What is the dose of IIV-Adj for children 6-23 months of age and route of administration?
7.5ug HA/0.25ml
IM
What is the dose of IIV-Adj for adults age 65 and older and the route of administration?
15ug HA/0.5ml
IM
How is the split virus vaccine produced?
with a detergent to disrupt the viral enveloppe
Describe the FluMist Quadrivalent (LAIV4) vaccine.
live attenuated
quadrivalent
for age 2-59yrs
intranasal spray; 0.1ml per nostril
What are the contraindications for FluMist Quadrivalent (LAIV4)?
children <24mo
severe asthma
children receiving ASA
pregnant women
immunocompromised
receipt of anti-influenza drugs in last 48hrs
Which influenza vaccine is not recommended for health care workers?
LAIV4 (FluMist Quadrivalent)
Which influenza vaccine is a great option for people that want protection but are scared of needles?
LAIV4 (FluMist Quadrivalent)
-intranasal spray
What are the common side effects of FluMist Quadrivalent (LAIV4)?
nasal congestion
runny nose
How long should an LAIV recipient avoid contact with immunocompromised patients for?
2 weeks following vaccination
What are the factors that cause for variation in effectiveness of influenza vaccines?
age
immunocompetence
match of vaccine to circulating virus
True or false: immunization of school aged kids would decrease mortality in older adults
true
kids are a huge reservoir for spreading influenza
True or false: influenza vaccine decreases the incidence of pneumonia, hospital admission, and death in the elderly
true
What happens in the body once the influenza vaccine is administered?
production of IgG antibodies to the viral HA and NA
How long does it take for protection to occur from the influenza vaccine? How long does protection last?
~2 weeks (counselling point)
~6 months
How long does protection from the influenza vaccine last in the elderly?
~4 months
When is it best to vaccinate for influenza?
late fall (October/November)
-provide AB throughout flu season
-better late than never
Who will have a reduced antibody response to the influenza vaccine? Is it worth vaccinating them?
very elderly, immunocompromised, renal failure
yes, you see attenuation of the disease
-decreased severity of illness
-decreased risk of death
-decreased rate of hospitalization
Which groups are part of the NACI statement regarding recommended recipients of the influenza vaccine?
pregnant women
adults and children with the following conditions:
-cardiac or pulmonary disease
-diabetes and other metabolic diseases
-cancer, immunocompromised
-renal disease
-anemia or hemoglobinopathy
-neurologic or neurodevelopment conditions
-morbid obesity (BMI>40)
-long term ASA treatment
residents of nursing home
age>65
children 6-59 months
indigenous people
people capable of transmitting to those at high risk
Why do we not give the influenza vaccine to children less than 6 months of age?
they dont develop an adequate antibody response
What is the dosing of the influenza vaccine for first time children <9 yrs old?
2 dose with minimum interval of 4 weeks
-everyone else is single dose
True or false: COVID-19 vaccines cannot be administered at the same time as, or any time before or after influenza immunization
false
NACI recommends children 6mo-5yrs wait 14 days between COVID-19 vaccines and non-COVID-19 vaccines
What are the adverse effects of the influenza vaccine?
can NOT cause influenza as vaccine does not contain live virus
-except FluMist
soreness at injection site (up to 48hrs)
fever, malaise, myalgia
-starts in 6-12rs, lasts 1-2 days
-just an immune response
oculo-respiratory syndrome (ORS)
Describe ORS.
red eyes
respiratory symptoms (cough, sore throat, difficulty breathing, chest tightness, wheezing)
facial edema
within 24 hrs of immunization and lasting <2 days
-mild and self-resolving
-not a CI to future vaccination
True or false: there is proven links of the influenza vaccine to autism, there is lots of mercury in the influenza vaccine, and the influenza vaccine overwhelms the immune system
false
What are the contraindications to the influenza vaccine?
anaphylaxis to previous dose
anaphylactic reaction to components of vaccine
-except egg
developed Guillain-Barre syndrome within 6wks of previous vaccine
True or false: we should delay vaccination to someone with minor or moderate acute illness
false
dont delay vaccination for a little cough
What might be the reasons for low rates of influenza vaccine utilization?
fear of se
believe vaccine is ineffective, unnecessary or causes flu
dont believe they will get sick
What are strategies to increase the use of the influenza vaccine?
standing order policies in hospital and LTC
at discharge from hospital or ER
promotion where high risk patients will see
increase accessibility
collaborating with HCP
What is our role as a pharmacist with the influenza vaccine?
educate patient
identify high-risk patients
host clinics
lead by example (get immunized)
What is the usage of neuraminidase inhibitors?
prevention and treatment of influenza
-effective against influenza A and B
What is the MOA of neuraminidase inhibitors?
competitively binds NA active site, thus impeding sialidase activity and release from cells
-without NA, the virus is not released from the infected cell
What are the NA inhibitors?
oseltamavir (Tamiflu)
zanamivir (Relenza)
What will NA inhibitors do for the patient?
decrease severity of symptoms
earlier resolution of symptoms by 1-1.5 days
may reduce hospitalization in high risk patients
oseltamivir may reduce mortality
What is the use of zanamivir?
treatment and prophylaxis of influenza in patients at least 7 years old
How much zanamivir is systemically absorbed?
10-20% (remember, its a diskhaler)
Describe the usage of zanamivir for treatment of influenza.
inhale 10mg (2 inhalations) BID x 5 days
must be started within 48 hours of symptoms
may be used longer in those with severe immunodeficiency who remain symptomatic
When is treatment with zanamivir indicated?
individuals with severe illness
those likely to develop complications or die
Describe the usage of zanamivir for prophylaxis of influenza.
inhale 10mg OD x 10 days
When should zanamivir be used cautiously?
patients with lung disease
-may exacerbate lung condition
What are the side effects of zanamivir?
although a lot of side effects were reported (headache, cough, sore muscles, etc) there were no differences between drug and placebo
-not too much concern over side effects
What is the use of oseltamivir?
treatment and prophylaxis in patients at least 1 years old
begin with 48 hours of symptoms
What is the dosing of oseltamivir treatment in adults (13yo)? What about pediatrics?
75mg BID x 5 days
age/weight based
Which NA inhibitor requires adjusted dosing based on renal function? What is the ClCr that requires the reduced dosing?
oseltamivir
ClCr <60ml/min
What is the dosing of oseltamivir prophylaxis in adults?
75mg daily
10 days unless the patient is a child or over the age of 65, then used for 14 days
What are the adverse effects of oseltamivir?
nausea & vomiting (take with food)
headache
What are the drug interactions associated with oseltamivir?
probenecid (increases exposure to active metabolite x2)
clopidogrel (prevents conversion to active metabolite)
True or false: antiviral resistance is common with zanamivir and oseltamivir
false
rare with zanamivir
seen with oseltamivir but uncommon
When is antiviral resistance most common with oseltamivir and zanamivir?
immunocompromised patients
prolonged therapy
Who does not need antiviral treatment for influenza?
healthy patients with mild, self-limited influenza
Who receives antiviral treatment for influenza?
those with severe disease (require hospitalization)
risk factors for poor outcomes
pregnancy and up to 4 weeks post partum
True or false: seasonal prophylaxis for influenza is not practical
true
When is post-exposure prophylaxis effective for influenza?
initiated in 48 hours of exposure
early treatment is preferred
Who receives influenza prophylaxis during an influenza A or B outbreak among high-risk residents of institutions or closed facilities?
all residents not already ill with the flu
unvaccinated staff
those with influenza receive antiviral treatment
How long is influenza prophylaxis performed during an outbreak of a high-risk institution?
minimum 8 days after onset of last case
What are the symptomatic treatments for influenza?
fever+myalgia: analgesics/antipyretics
cough: cough suppressants
sore throat: lozenges, saline gargle
HYDRATION IS KEY (symptoms exacerbated by dehydration)
bed rest
stay home
