1. School-Based Immunization for Control of Influenza?
Harry F. Hull, M.D.
State Epidemiologist
Minnesota Department of Health
Saint Paul, MN

2. Influenza >220,000 excess hospitalizations/yr 43% 65+ yrs
>36,000 deaths/yr
>90% 65+ yrs

3. Need for New Approaches to Influenza Control
Highest risk populations inadequately protected by vaccination
Insufficient demand for manufacturers to expand production capacity
Responding to pandemic influenza with inadequate vaccine supply

4. Percent of Persons 65+ years of age who Received Influenza Vaccine (Red) or PPV (Blue), 1989-2002
2010 Goal: 90%
2000 Goal: 60% 
Medicare Pays for Influenza Vaccine (1993)
Influenza vaccine shortage season
From: McBean, Hebert, Park , Caldwell.Influenza Vaccines for the World, Lisbon, Portugal, May 24, 2004

5. Ratios of rates of Influenza-associated P&I Hospitalizations Comparing Older Age-groups to those years of age
From: McBean, Hebert, Park , Caldwell.Influenza Vaccines for the World, Lisbon, Portugal, May 24, 2004

6. Inactivated Influenza Vaccine
Elderly persons in community
No protection for ILI
Reduced hospitalization
I&P -27%
Respiratory disease – 22%
Cardiac – 24%
Reduced all cause mortality – 47%
Healthy young adults
90% effective against ILI
Jefferson et al. Lancet 2005;366:

7. Need for New Approaches to Influenza Control
Highest risk populations inadequately protected by vaccination
Insufficient demand for manufacturers to expand production capacity
Responding to pandemic influenza with inadequate vaccine supply

8. Herd Immunity
High population immunity protects few non-immune against disease
Measles in U.S.
Global polio eradication

9. Herd Immunity
Immunization of highest risk groups protects larger non-immune population
Smallpox eradication
US stopped immunization in 1971
Last case of smallpox 1977
Pneumococcal Conjugate Vaccine
83% decline in invasive disease among black children <2 yrs in TN with 31% coverage*
55% decrease in invasive disease >50 yrs**
Prevents 2x as many cases in unvaccinated than in vaccinated***
*Talbot et al. PICJ 2004: 23:726-31
**Lexau et al. JAMA. 2005;294:
***MMWR 2005;54:893-7

10. Herd Immunity for Influenza
Household contacts of infants
Household contacts of high risk with chronic disease, immune suppression
Health care workers

12. School Children and Influenza Asian Flu, 1957
Highest attack rates in school children*
10-19 yrs – 1/2 ill, <9 yrs – 1/3 ill
20-39 yrs - 1/4 ill, 40+ yrs – 1/6 ill
School children first to become ill **
High school > elementary > adults & preschool
*Chin et al. Pub Hlth Rep ;149-58
**Dunn et al. Am J Hyg 1959;70:

13. Timing of Pediatric and Adult Influenza Infections

14. School Children Infect Families
Seattle Virus Watch*
Children aged 5-9, yrs had highest rates of introducing influenza virus into families
Families with school children and/or day care children had the highest attack rates
Kansas City, 1957**
80% of index cases yrs
*Fox et al. AJEpidem 1982; 116:
**Chin et al. Pub Hlth Rep ;149-58

15. Children Are Efficient Spreaders
Children more likely to become ill with symptoms that promote transmission
Children shed influenza virus at higher titer and for longer periods*,**
4.5 vs 3.5 logs
6 vs 4 days
* Treanor et al. JAMA Feb 23;283(8):
**Whitley et al. Pediatr Infect Dis J. 2001; 20:

16. Closing Schools Alters Influenza Outbreaks
42% decline in physician visits for respiratory illness in 6-12 yr olds during a 2- week teachers strike during an influenza outbreaks in Israel
Hurwitz et al. PIDJ 2004;23:675-7

17. Impact of Influenza Vaccination of Day Care Children on Household Contacts
All contacts
42% reduction in febrile URI
School aged contacts
80% reduction in febrile URI
70% reduction in school days missed
100% reduction in parents missing work
91% reduction in physician visits
88% reduction in antibiotic prescriptions
45% reduction in over the counter medications
Hurwitz et al. JAMA 2000

18. School-based Immunization
Immunization of 86% of school children in Tecumsah, MI in 1968 reduced illness in all age groups by 67% compared with a neighboring unvaccinated community
Monto et al. JID 1970; 122:16-25.

19. Five-Year Moving Average Excess Deaths Pneumonia and Influenza and All Causes USA and Japan,
50-85% of children yrs vaccinated
75-80% reduction in adult deaths during immunization program
1 death prevented for every 420 children immunized
Vaccination Program Begins
Vaccination Optional
Vaccination Program Ends
Reichert et al. NEJM, 2001

20. Models of Influenza Immunization School Children Aged 5-18 yrs
20% coverage reduces childhood influenza by 49% and adult influenza 43%*
20% coverage reduces mortality in >65’s better than 90% coverage in >65’s**
20% coverage yields cost savings of $443 per vaccinated child (Direct - $89)*
80% coverage reduces all influenza 91%*
80% coverage yields cost savings of $174 per vaccinated child (Direct - $35)**
70% coverage sufficient to stop an outbreak+
*Weyker et al. Vaccine 2005;23:
**Halloran & Longini. Science 2006; 311:615-6.
+ Longini et al. AJEpidem 2005:161:

21. Live, Attenuated vs Inactivated Influenza Vaccine
Live, Attenuated Influenza Vaccine
Efficacy in children
80% LAIV vs 65% IIV children*
Decreased duration and severity of illness
Increased Secretory IgA
Viral shedding decreased 83%**, IIV none***
High efficacy with 1 dose
89% 1 dose, 94% 2 doses, children 15-71m+
Cross protection for poor match years
URI decreased 86%, LRI decreased 100%++
*Negri E, et al. Vaccine Apr 22;23(22):
**Belshi et al. JID 2000; 181:1133-7
***Johnson et al JID 1986; 154:121-7
+Belshi et al. NEJM 1998; 338:
++Belshi et al. J Pediatrics 2000;136:168-75

22. Spanish Influenza of