novel influenza a (h1n1): impact on schools, spring, 2009
DESCRIPTION
Novel Influenza A (H1N1): Impact on Schools, Spring, 2009. 30 July 2009 Francisco Averhoff MD, MPH Community Measures Task Force Division of Global Migration and Quarantine Centers for Disease Control and Prevention. 2. Basis for Recommendations: Non-Pharmaceutical Interventions (NPIs). - PowerPoint PPT PresentationTRANSCRIPT
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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
2
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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
#1
#2
#3
Days since First Case
Pandemic outbreak:No intervention
Pandemic outbreak:With intervention
11
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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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6000
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10000
12000
14000
16000
Date
Death
s R
ate
s /
100,0
00 P
op
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tio
n
(An
nu
al
Basis
)
Philadelphia
St. Louis
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16
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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
0
100000
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pr
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pr
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ay
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ay
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19-M
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de
nts
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d (
Lin
e)
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ho
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Dis
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olu
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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
0
100000
200000
300000
400000
500000
600000
700000
27-A
pr
29-A
pr
1-M
ay
5-M
ay
7-M
ay
11-M
ay
13-M
ay
15-M
ay
19-M
ay
21-M
ay
26-M
ay
28-M
ay
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3-Ju
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5-Ju
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9-Ju
n
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un
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1200
Schools Closed
Students Affected
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200000
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500000
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700000
27-A
pr
29-A
pr
1-M
ay
5-M
ay
7-M
ay
11-M
ay
13-M
ay
15-M
ay
19-M
ay
21-M
ay
26-M
ay
28-M
ay
1-Ju
n
3-Ju
n
5-Ju
n
9-Ju
n
11-J
un0
200
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1000
1200
Schools Closed
Students Affected
June 17 – Endedschool dismissal
surveillance
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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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1/1/09 1/29/09 2/26/09 3/26/09 4/23/09 5/21/09
ILI
visi
ts
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