2. What is influenza?
Influenza, commonly known as “the flu”, is a highly
contagious infection of the airways caused by
influenza viruses.
It is often referred to as “seasonal” influenza
because these viruses circulate annually in the
winter season in the northern hemisphere.
The timing and duration of influenza season varies
-outbreaks can happen as early as October but
most often activity peaks in January or later.
Late season outbreaks occurring in April and even
May have also been reported.
3. A, B and C influenza viruses
Influenza A and B viruses cause seasonal
epidemics, while type C viruses cause mild
respiratory illness
Influenza A viruses are classified into different strains
or subtypes based on two proteins or antigens on the
virus surface: hemagglutinin (H) and neuraminidase
(N) e.g., H1N1 and H3N2
Influenza B viruses can be classified into two
antigenically distinct lineages, Yamagata and Victoria
like viruses
Influenza A and B strains are included in each year's
influenza vaccine
The vaccine does not protect against influenza C
4. Signs and symptoms of
influenza
Sudden onset
Typically starts with a headache, chills and cough,
followed rapidly by fever, loss of appetite, muscle
aches and fatigue, runny nose, sneezing, watery
eyes and throat irritation
Nausea, vomiting and diarrhea may also occur,
especially in children
5. How is influenza spread?
The virus is spread mainly from person to person
when those with influenza cough or sneeze (droplet
spread)
The droplets are propelled about 3 feet through the
air
People may also become infected by touching an
object or a surface that has the influenza virus on it
and then touching their mouth, eyes or nose
6. Impact of Influenza-United States,
1990-1999
Approximately 36,000 influenza-associated
deaths during each influenza season
Persons 65 years of age and older account for
more than 90% of deaths
Higher mortality during seasons when influenza
type A (H3N2) viruses predominate
7. Impact of Influenza-United States,
1990-1999
Highest rates of complications and hospitalization
among young children and person 65 years and
older
Average of more than 200,000 influenza-related
excess hospitalizations
57% of hospitalizations among persons younger
than 65 years of age
Greater number of hospitalizations during type A
(H3N2) epidemics
8. Influenza vaccine development
Each February, the World Health Organization (WHO)
provides a recommendation on the strains to be
included in the influenza vaccine for the northern
hemisphere
Two influenza "A" viruses and one influenza "B" virus
are selected based on the characteristics of the
current circulating influenza virus strains (two "B"
viruses are selected for quadrivalent vaccines)
A new vaccine is reformulated each year to protect
against new influenza infections
Each vaccine lot is tested on healthy individuals to
ensure the vaccine is safe and effective
9. Influenza vaccine development
(cont’d)
There are currently eight trivalent influenza vaccines
licensed for use in Canada
Seven are trivalent inactivated influenza vaccine
(TIV)
One is a live attenuated influenza vaccine (LAIV)
There are currently three quadrivalent influenza
vaccines licensed for use in Canada
Two are quadrivalent inactivated influenza vaccine
(QIV)
One is a live attenuated influenza vaccine (QLAIV)
For the 2014–2015 influenza immunization program,
Alberta will be using three TIV products and one
QLAIV product
10. How does inactivated influenza
vaccine work?
Both humoral and cell-mediated responses play a role
in immunity
Administration of inactivated influenza vaccine results
in the production of circulating IgG antibodies to the
viral haemagglutinin as well as a cytotoxic T
lymphocyte response
Humoral antibody levels, which correlate with vaccine
protection, are generally achieved 2 weeks after
immunization and immunity usually lasts less than 1
year
Initial antibody response may be lower in the elderly
and immune.
11. How does live attenuated influenza
vaccine work?
Immune mechanisms conferring immunity following
administration of live attenuated vaccine are not fully
understood
Administered by the intranasal route, QLAIV is
thought to result in an immune response that mimics
that induced by natural infection with wild-type virus,
developing both mucosal and systemic immunity
Serum antibodies, mucosal antibodies and influenza-
specific T cells may play a role
The viral strains in QLAIV are engineered to be cold
adapted (can only replicate in the nasopharynx),
temperature sensitive (cannot replicate in the warm
temperatures of the lower airways and lungs) and
attenuated (unable to cause clinical disease)
12. Effectiveness of influenza vaccine
Vaccine effectiveness depends on the similarity between
vaccine strains and the strains in circulation during
influenza season
With a good "match," influenza immunization prevents
disease in 70 to 90% of healthy individuals
This drops to 30 to 40% in the frail and elderly
It does, however, prevent death in 85% of the frail and
elderly
It prevents hospitalization in 50 to 60% of individuals
immunized
Even with an imperfect match, Canadian studies show the
vaccine still reduces the overall risk of infection by about
40-60%
A vaccine that is not perfectly matched can still offer
13. Vaccine strains for 2014-2015
The strains that will be included in the 2014-2015
influenza vaccine for the Northern hemisphere are:
A/California/7/2009 (H1N1)pdm09-like virus
A/Texas/50/2012 (H3N2)-like virus
B/Massachusetts/2/2012-like virus
B/Brisbane/60/2008-like virus (B/Victoria lineage)
(Quadrivalent QLAIV only)
14. Facts about trivalent inactivated
influenza vaccine (TIV)
Is an inactivated (killed) vaccine –cannot cause
influenza disease in the vaccine recipient
The virus is grown in hens’ eggs, inactivated, broken
apart and highly purified
In addition to the antigen, the vaccine may contain:
Thimerosal (preservative in multidose vials)
Trace residual amounts of egg proteins,
formaldehyde, kanamycin, neomycin, cetyl trimethyl
ammonium bromide (CTAB), polysorbate 80, sodium
deoxycholate and sucrose
Check the product monograph as ingredients vary
with specific inactivated influenza vaccines
15. Facts about live attenuated
influenza vaccine (QLAIV)
Is a live vaccine –cannot cause influenza disease
in the vaccine recipient because the virus is
attenuated or weakened (however is
contraindicated in immuno compromised
individuals)
The virus is grown in specific pathogen-free eggs
from specific pathogen-free chicken flocks
In addition to the antigen, the vaccine may
contain:
Trace residual amount of arginine, gelatin
hydrolysate (porcine type A), gentamicin,
monosodium glutamate, ovalbumin and sucrose
Check the product monograph for other product
excipients
16. ages
6 months up to & including 8 years of age
2 doses
* if never been previously immunized with seasonal
influenza vaccine (spaced 4 weeks apart –minimum
interval)
1 dose only if previously immunized with seasonal
influenza vaccine
9 years of age and older
1 dose
*This recommendation applies whether or not the child
received monovalent pH1N1 vaccine in 2009-2010.
17. Reactions to inactivated influenza
vaccine
The majority of people do not have a reaction to TIV;
however some reactions that may occur are outlined
below. These reactions generally start 6 to 12 hours
after immunization and can last for 1 to 2 days
Common Reactions
Injection site redness, swelling, pain
Fatigue, headache, myalgia
Arthralgia, fever, chills, malaise
18. Reactions to live attenuated
influenza vaccine
Most people have no reaction to QLAIV. If reactions
occur they tend to be mild and last for 1-3 days,
peaking 2 days following immunization.
Common Reactions
Runny, stuffy nose in children and adults
Children –decreased appetite, headache, weakness
and fever
Adults –sore throat, headache, cough and weakness
For children requiring two doses of vaccine, the
symptoms tend to be less frequent following the
second dose.
