Novel Influenza A (H1N1): Impact on Schools, Spring, 2009
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Transcript of Novel Influenza A (H1N1): Impact on Schools, Spring, 2009
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Novel Influenza A (H1N1): Impact on Schools, Spring, 2009
30 July 2009
Francisco Averhoff MD, MPHCommunity Measures Task Force
Division of Global Migration and QuarantineCenters for Disease Control and Prevention
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Basis for Recommendations: Non-Pharmaceutical Interventions (NPIs)
• Evidence from 1918 pandemic
• Epidemiologic studies
• Modeling
• Common Sense
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Non-Pharmaceutical Interventions (NPIs)*
• Isolation and treatment of ill persons• Voluntary home quarantine of
household contacts• Dismissal of students from school and
social distancing and daycare closure• Workplace/community social distancing
* Targeted Layered Containment (TLC):The sum likely to be greater than the parts…
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Factors that Impact Transmission and Reproductive Rate (Ro)*
• Infectiousness of the infected• Susceptibility of uninfected• Interactions, contact and behaviors of
the population- target of interventions
* Goal is Ro < 1, results in decreasing epi curve and end of outbreak/epidemic
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Effect of R on Hypothetical Epidemic Curves
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Community-Based Non Pharmaceutical Interventions (NPIs)
1. Delay disease transmission and outbreak peak2. Decompress peak burden on healthcare infrastructure3. Diminish overall cases and health impacts
DailyCases
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Days since First Case
Pandemic outbreak:No intervention
Pandemic outbreak:With intervention
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Collins SD, Frost WH, Gover M, Sydenstricker E: Mortality from influenza and pneumonia in the 50 largest cities of the United States First Edition Washington: U.S. Government Printing Office 1930.
1918 Death Rates: Philadelphia v St. Louis
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Summary NPIs • Nonpharmaceutical interventions (NPIs) likely to be
effective in mitigating influenza pandemic
– Effectiveness unknown, will depend on implementation and compliance with interventions
– Multiple, early, interventions started early (targeted, layered containment) likely more effective than single intervention
– May be the only interventions available early in pandemic
– Consequences of interventions need to be considered
– Additional research needed
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Challenges, Spring, 2009• April, 2009: Early emergence of H1N1 in US, lack of
data on severity (suggestion from Mexico early of “moderate-high” severity) resulted in:
– Need for national school closure surveillance system– Need to develop/implement NPI policies with
insufficient data– School closure guidance/policies that deviated from
USG planning and required modifications with additional data
– Need to develop other/unanticipated NPI guidance: Public/mass gatherings, Post-Secondary Schools, Correctional Facilities, Summer Camp, Child Care, Other
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School Closure Surveillance, Spring 2009
• Methods– Definition
• Public/private, K-12• Dismissal/Closure >= 1 day• Attributed/associated novel influenza A or ILI
– April 27 – June 12, 2009– Media + state/local education website reviews– Direct reports to CDC, DOEd– Confirmation with district
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School Closures, Spring 2009
• Results: April 27 – June 12– 35 States and DC >= 1 school– 1351 (1%) schools dismissed/closed >= 1
day• Mean 3.8 days (range 1 – 9 days)• 5137 total days of school lost
– 824,000 students affected (3,170,000 student-days school lost)
QuarantineTM13Source: ED and CDC Confirmed School Closing Reports released each weekday at 2:00pm
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Number of school and student dismissals related to novel influenza A (H1N1), United States,
April 27 – June 12, 2009
May 5 - School dismissal
not recommended
May 1 - School dismissal
recommended for 14 days
Apr 27 - School dismissal
recommended for 7 days
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Schools Closed
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Schools Closed
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June 17 – Endedschool dismissal
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Observations
• Schools Responsive to CDC Recommendations– Pre-emptive dismissal/closure rarely employed – Sporadic– Impact on disease?
• Severity: Pandemic Severity Index (PSI): 2 or less– High Risk Persons at risk for hospitalization and death (eg
Asthma)
• Transmission: < seasonal influenza– Highest in school age– Maybe some protection with older age– Predominant modes: contact vs. droplet vs. air?
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ESSENCE: Total ILI and ILI among 5-17 year olds, Counties A and B, 2009
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County A County A age 5-17 County B County B age 5-17
* Influenza-like illness, chief complaint of emergency department visits reported to ESSENCE
Spring break H1N1 school closureWinter break(County A)
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Proportion of 5-17 year olds with ILI: comparison when schools open or closed,
Counties A and B, Jan – June 2009
50%50%School Open
75% 25%School Closed
Other Ages5 – 17
year olds
RR= 0.5 95% CI: [0.47, 0.53] p=.0001
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Ongoing NPI Studies (CDC)
• School Closure/Dismissal & Other– Effectiveness – KAB including Adherence to Recommendations
• Ill students/teachers stay home• Quarantine• Re-congregation • Hygiene
• Consequences of School Closure– economic and other
• Other & Community NPIs– Social Distancing
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Next Steps• Goals of interventions
– Reduce Morbidity and Mortality– Minimize Social Disruption
• Effectiveness of School Closure/Dismissal (Spring and Summer)– Review Spring experience (descriptive epidemiology)– Summer Camp experience– International experience
• Establish Surveillance & Monitoring for Fall– School dismissal/closure– Other– Real-time evaluation and feedback
• Effectiveness of NPIs – Isolation, Quarantine, Social Distancing (including School
Closure/Dismissal), Hygiene, PPE