Transcript Flue vaccine - An-Najah National University

Flu
Vaccination in
Children 2008
Samar Musmar,MD,FAAFP
Vice Dean for Clinical Affairs
An-Najah National University
Faculty of Medicine
Head, Medicine and Society Dep.
Objectives
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Biology of Influenza
Influenza complications
Influenza epidemiology
Influenza Control
Influenza vaccine
Effectiveness of vaccine
SE of TIV flu vaccine
LAIV
Recommendations for flu
Vaccine in Children
• Antiviral medications
Human Influenza Virus
(Flu)
Influenza
• Highly transmissible respiratory
illness caused by influenza viruses
• 3 types A,B,C
• Yearly winter epidemics (seasonal
or interpandemic influenza)
• Sporadic, unpredictable pandemics
Influenza virus type A
• Subtyped based on surface glycoproteins
• 16 hemagglutinin (HA) and 9
neuraminidase (NA)
• Current human subtypes: H1N1 &
H3N2
• Capable of epidemics and pandemics
• Antigenic shift--pandemics and drift—yearly
epidemic
• Infects multiple other species and can jump
between them
• Birds, pigs, horses, dogs…
• Birds are the reservoir for new subtypes:
H1-16
Influenza Virus Types B and C
• Influenza B
• Humans only reservoir
• Less mortality in most years c/w type A
• Associated with epidemics, not pandemics
• One influenza B strain in the annual
seasonal influenza vaccine
• Influenza C
• Causes mild disease, sporadic cases
• Not included in vaccine
Why to use vaccine?
• Complication in Children
1.Serious illnesses----hospitalization
(Influenza pneumonia mainly)
2.Influenza-associated deaths – uncommon
• data indicate -- although deaths are more
common among children with risk factors for
influenza complications, the majority of
pediatric deaths occur among children of all
age groups with no known high-risk
conditions
Annual Interpandemic Influenza
Impact*
• 2.5-20% of population ill
• Highest rates in children
• Attack rates over 30% in children reported
• Average of >36,000 deaths (wide range)
• >90% in those >64 years
• Average of >200,000 hospitalizations (wide range)
• About 50% in those >64 years
• Risk of hospitalization for children <2 years similar to elderly
• Substantial economic impact
• Burden of annual epidemics estimated at $87.1 billion annually
Influenza Laboratory-Confirmed
Cumulative Hospitalization, Children 0 4 Years, 2007- 08 and Previous 4
Seasons
Population-Based Rate per 10,000 Children
14
12
10
8
6
4
2
0
40-41 42-43
44-45
46-47
48-49
50-51
52 -1
2-3
4-5
6-7
8-9
10-11
12-13 14-15
2007-2008 Influenza Season 2 Week Reporting Period
2003-2004
2004-2005
2005-2006
2006-2007
2007-2008
16-17 18-19 20-21
Average Influenza-Associated
Illness Rates by Age Group*
40%
Illiness rates
35%
Michigan
Houston
30%
25%
20%
15%
10%
5%
0%
<5
5 to 14
Sources: Monto J Infect Dis
Glezen N Engl J Med
15 to 24
Age group
25 to 60
>60
Types of Flu vaccine
• Trivalent inactivated influenza vaccine (TIV)
1.Annual
2.Any person aged >6 months
• Live, attenuated influenza vaccine (LAIV)
1.Annual
2.Healthy, nonpregnant persons aged 2--49 years
Determinants of Antibody
Response to Influenza Vaccines
• Age
• Elderly, infants and chronically ill generally lower antibody
response
• Prior exposure to virus strains similar to those in vaccine
(infection or previous vaccination)
• Immune competence of person being vaccinated
• Amount of antigen in vaccine
• Virus – strains can vary as to how robust immune responses
will be
Inactivated Vaccine Effectiveness
by Age and Risk Group
Age/Risk group
Outcome
Effectiveness*
6m-16 years, healthy
Influenza
50-90%
18-64 years, healthy
Influenza
50-90%
>65 years, community
Influenza
30-70%
Elderly, nursing home
Influenza
30-40%
Elderly, nursing home
Hospitalization
30-60%
*Overall range from studies conducted when good antigenic match
between vaccine and circulating strains with lab-confirmed influenza.
Effectiveness may be lower when vaccine and circulating strains
antigenically different.
New and Updated
Recommendations from the
Advisory Committee on
Immunization Practices (ACIP)
New from the ACIP: Influenza
Vaccination Recommendations
for Children
All children aged 6 months through 18
years should receive annual influenza
vaccination, beginning in 2008 if
feasible, and beginning no later than
during the 2009-2010 influenza season
Timeline of ACIP Recommendation Changes
for use of Influenza Vaccine
Before 2000:
Persons aged 65 or older
Persons with chronic medical conditions that make them
more likely to have complications of influenza
Pregnant women in the second or third trimester
Contacts (household and out of home caregivers) of the above groups
Healthcare workers
2000:
Adults 50 and older
2004:
Children aged 6--23 months
Contacts (household and out of home caregivers) of
children aged 0--23 months
Women who will be pregnant during influenza season
2006:
Children aged 6--59 months
Contacts (household and out of home caregivers) of
children aged 0-59 months
2008:
All children aged 6 months—18 years
Rationale for Expanding Vaccination
Recommendations to Include all Schoolage Children and Adolescents*
Rationale
• Evidence that influenza has substantial adverse impacts among school age
children and their contacts (e.g., increased school absenteeism, antibiotic use,
medical care visits, and parental work loss)
• Evidence that influenza vaccine is effective and safe for school-age children
• The expectation that a simple age-based influenza vaccine recommendation
will improve current low vaccine coverage levels among the approximately
50% of school-age children who already had a risk- or contact-based indication
for annual influenza vaccination
Also noted
• The potential for the indirect effect of reducing influenza among persons who
have close contact with children, and reducing overall transmission within
communities, if sufficient vaccination coverage among children can be
achieved
*Approved at February 27, 2008 ACIP meeting.
Begins in 2008-09 influenza season
Other options “Antiviral drugs”
• Adjunct to vaccination
• Effective when administered as treatment and when used for
chemoprophylaxis after an exposure to influenza virus
• Amantadine and rimantadine
– effective against influenza A only
– approved for treatment and prophylaxis
– High Levels of Adamantane Resistance Among
Influenza A (H3N2) MMWR 05-06
• Zanamivir (aged >7 year) and oseltamivir (aged >1 years)
– neuraminidase inhibitors
– effective against influenza A and B
– Oseltamivir(Tamiflu) approved for prophylaxis
Antiviral Resistance 2008 USA
• Neuraminidase Inhibitor Resistance :
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(11%) A (H1N1) viruses resistant to oseltamivir
• Was (0.7%) in 2005-2006
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0 (H3N2) viruses resistant to oseltamivir
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0 B viruses resistant to oseltamivir
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All tested viruses remain sensitive to zanamivir
–
Given type/subtype prevalence in the United States, low rate of overall
resistance (~2%)
• Adamantane Resistance
– 14% influenza A (H1N1) viruses tested were resistant
– (99%) influenza A (H3N2) viruses tested were resistant
Other options
Nonpharmacologic interventions
• Advising frequent hand washing and improved
respiratory hygiene
• Reasonable and inexpensive
• Have been demonstrated to reduce respiratory
diseases but
• Have not been studied adequately to determine
if they reduce transmission of influenza virus
Universal flu vaccine
• intended to provide protection against all
‘A’ strains of the virus that causes human
influenza, including pandemic strains
• Will not need to be renewed annually
• targets M2e(matrix protien 2 ectodomain)
a relatively invariant viral determinant
• Successful clinical trials, animal ,phase I
human
Other Key Updates in the 2008 ACIP
Influenza Vaccine Recommendations
• Either TIV or LAIV should be used when vaccinating healthy persons
aged 2--49 years
• 2 doses separated by >4 weeks for children aged 6 months—8
years receiving vaccination for the first time
• Children 2—4 years old should be screened for reactive airways
disease before receiving LAIV (MMWR Nov 23 2007)
• “Healthy” means no underlying chronic illness that confers
increased risk for influenza complications
• All new 2008–2009 trivalent vaccine virus strains
• A/Brisbane/59/2007 (H1N1)-like
• A/Brisbane/10/2007 (H3N2)-like
• B/Florida/4/2006-like
– Neuraminidase inhibitors (oseltamivir or zanamivir) remain drugs of
choice in prevention or treatment
• High levels of resistance among adamantane class drugs
Thank You for your Attention