Seasonal Influenza Vaccination in Europe
Thomas D. Szucs, MD Patricia R. Blank, PhD Institute of Pharmaceutical Medicine European Center of Pharmaceutical Medicine University of Basel Switzerland
Overview
• On efficacy and effectiveness
• On policy • On economics
3
3
Efficacy* / Effectiveness** of Influenza Vaccination in different population segments
* Efficacy = randomized, controlled trials ** Effectiveness = observational trials
How to Define Influenza? No gold standard clinical case definition for influenza URI
Influenza Illness Influenza infection
Lab confirmed influenza ILI
Hosp / Death
Implications of the heterogeneity of influenza case definitions: care must be exercised in interpreting and comparing the results of studies assessing vaccine efficacy and effectiveness K.L. Nichol / Vaccine 24 (2006) 6726–6728
How to Define Influenza? No gold standard clinical case definition for influenza Lab confirmed influenza 89%
100
Vaccine effectiveness
90
ILI
80 70 60 50
63% Acute respiratory illness
60%
40 30
28%
20 10 0
Specificity
Influenza Vaccine in CommunityDwelling Elderly
Cohort studies
RCTs
Outcome
Risk Ratio
95% CI
Flu-like illness
0.59
(0.47, 0.73)
Influenza
0.42
(0.27, 0.66)
Influenza admissions
0.52
(0.30, 0.90)
Deaths (all cause)
1.02
(0.11, 9.72)
Flu-like illness
1.05
(0.58, 1.89)
Influenza
0.19
(0.02, 2.01)
Resp admissions
0.88
(0.54, 1.43)
Influenza admissions
0.72
(0.62,0.85)
Deaths (influenza)
0.87
(0.70, 1.09)
Deaths (all cause)
0.58
(0.45, 0.67)
The choice of the outcome can dramatically affect the numbers reported Jefferson T, Cochrane Review
Randomized Placebo-controlled Trials Among Young Adults Efficacy of Inactivated Vaccine Against Lab-confirmed* Influenza, Michigan
Season
Placebo (%+)
Trivalent Inactivated Vaccine (%+)
2004-20051
7.8
1.9
75% (42 to 90)
2005-20062
1.8
1.5
16% (-171 to 70)
2007-20083
10.8
3.4
68% (46 to 81)
Vaccine Efficacy (95% CI)
1. Ohmit SE, et al. N Engl J Med. 2006;355:2513-2522. 2. Ohmit SE, et al. J Clin Infect Dis. 2008;198:312-317. 3. Monto AS, et al. N Engl J Med. 2009;361:1260-1267. Fiore, CDC, Atlanta
*Culture and/or polymerase chain reaction (PCR) assay. CI = confidence interval.
TIV Effectiveness Estimates by Age and Risk Group When Vaccine Strains Match Circulating Strains, Using a Variety of Study Designs
Age/Risk Group
Outcome
Effectiveness*
6 months-18 years
Influenza†
50-90%
18-64 years
Influenza†
50-90%
>65 years, community
Influenza†
50-70%
Influenza†
30-40%
Hospitalization or death
40-80%
Elderly, nursing home Pregnant women
Influenza in newborn† ILI in mother
63% 36%
* Effectiveness is lower when vaccine and circulating strains are antigenically different. No vaccine effectiveness is sometimes observed when the prevalence of antigenically different strains is high. CDC. MMWR Morb Mortal Wkly Rep. July 12, 2009;58:1-52.
†Laboratory-confirmed influenza virus infection.
Fiore, CDC, Atlanta
Recommendations on influenza vaccination are getting stronger worldwide
WHO guidelines
European Union recommendations
2010 ACIP recommendations
Target:
Target:
Universal vaccination
75% coverage for the adults over 65 by 2010/2011 1
75% coverage for the adults over 65 by 2014/2015 2
for people aged 6 months and older 3
Overall, more than 50 countries fund influenza vaccination to nationally defined high-risk groups 1 1) World Health Organization. Wkly Epidemiol Rec 2005; 33: 277–288. 2) EPHA. Council recommendation of 22 December 2009 on seasonal influenza vaccination. 3) ACIP. Prevention and Control of Influenza with Vaccines Recommendations of the Advisory Committee on Immunization Practices (ACIP), 2010. MMWR, August 6, 2010; 59(rr08):1-62
Global coverage Russia
Estonia Latvia Lithuania Poland Denmark United Kingdom Czech Republic Bulgaria Serbia Spain Portugal Turkey Morocco Tunisia Algeria Venezuela
Mexico
South Korea China Saudi Arabia
Brazil
South Africa
Chile Uruguay Argentina
Sanofi Pasteur internal data (2010)
Malaysia Singapore
40-60% 20-40% 10-20% 5-10%
