Video 8.5: School closure

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Epidemics

33 classificações

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The University of Hong Kong

Epidemics

33 classificações

“If history is our guide, we can assume that the battle between the intellect and will of the human species and the extraordinary adaptability of microbes will be never-ending.” (1) Despite all the remarkable technological breakthroughs that we have made over the past few decades, the threat from infectious diseases has significantly accelerated. In this course, we will learn why this is the case by looking at the fundamental scientific principles underlying epidemics and the public health actions behind their prevention and control in the 21st century. This course covers the following four topics: 1. Origins of novel pathogens; 2. Analysis of the spread of infectious diseases; 3. Medical and public health countermeasures to prevent and control epidemics; 4. Panel discussions involving leading public health experts with deep frontline experiences to share their views on risk communication, crisis management, ethics and public trust in the context of infectious disease control. In addition to the original introductory sessions on epidemics, we revamped the course by adding: - new panel discussions with world-leading experts; and - supplementary modules on next generation informatics for combating epidemics. -------------------------------------------------------- (1) Fauci AS, Touchette NA, Folkers GK. Emerging Infectious Diseases: a 10-Year Perspective from the National Institute of Allergy and Infectious Diseases. Emerg Infect Dis 2005 Apr; 11(4):519-25. What you'll learn - Demonstrate knowledge of the origins, spread and control of infectious disease epidemics - Demonstrate understanding of the importance of effective communication about epidemics - Demonstrate understanding of key contemporary issues relating to epidemics from a global perspective

Na lição

Theme Three: Control (Non-pharmaceutical intervention (NPI))

Theme Three Summary

Week 8 Introduction1:42

Week 8.1: Non-pharmaceutical interventions overview and John Snow4:34

Week 8.2: Control of Cholera8:37

Week 8.3: Hygiene and other personal interventions6:23

Video 8.4: Isolation and quarantine and contact tracing6:02

Video 8.5: School closure7:49

Video 8.6: International measures including travel restrictions and entry screening4:40

Video 8.7: Zoonoses - market closure6:18

Conheça os instrutores

Gabriel M. Leung (HKU)
Dean
Li Ka Shing Faculty of Medicine
Joseph T. Wu (HKU)
Associate Professor
Li Ka Shing Faculty of Medicine
Kwok-Yung Yuen (HKU)
Professor
Li Ka Shing Faculty of Medicine
Tommy Lam (HKU)
Assistant Professor
Li Ka Shing Faculty of Medicine
Maria Huachen Zhu (HKU)
Associate Professor
Li Ka Shing Faculty of Medicine
Guan Yi (HKU)
Chair Professor
Li Ka Shing Faculty of Medicine
Benjamin Cowling (HKU)
Professor
Li Ka Shing Faculty of Medicine
Thomas Abraham (HKU)
Associate Professor
Journalism and Media Studies Centre
Mark Jit (LSHTM)
Professor
Department of Infectious Disease Epidemiology
Malik Peiris (HKU)
Chair Professor
Li Ka Shing Faculty of Medicine
Marc Lipsitch (Harvard)
Professor
Department of Epidemiology

In this part, I will talk about school closures,

a non-pharmaceutical intervention

at the community level.

After completing this part,

you should be able to explain

why school-age children are important

in transmission of some infectious diseases,

to describe the potential impact of school closures,

and to discuss the practical difficulties

associated with closing schools.

It is well known that school-age children

are of primary importance in the transmission

of many respiratory infections in the community.

A survey of social contact patterns,

in eight European countries,

identified children as the group

with the greatest frequency of contacts.

The heat plot, shown here,

indicates the frequency of social contacts,

with highest frequency shown in white.

We can clearly see the frequency

of contacts between children is high.

The diagonal band indicates that contacts

tend to be most frequent

among people of similar ages,

and the two off-diagonal bands show the contacts

between children and their parents.

The investigators considered what would happen

if a new pathogen emerged

in a completely susceptible population

and was spread through close contacts

as, for example, a respiratory virus might be.

Based on these patterns,

the investigators determined

that incidence of infections with the new pathogen

would be highest in children.

Influenza virus spreads through close contact,

and rates of infections in children

tend to be higher than in other age groups

in influenza epidemics and pandemics.

That is not to say that children

have the greatest burden of severe disease,

because influenza virus infections are often milder

in children than in adults and the elderly.

Because of the high rate of infections in children,

and particularly in schools,

the closure of schools during epidemics

is a non-pharmaceutical intervention

with particular promise.

Going back a hundred years,

the 1918 influenza pandemic

had a devastating impact on the world.

School closure was a common intervention

used in many locations to try to slow transmission,

and there is some evidence

that early implementation

of school closures was effective.

School closures were also used

in other pandemics and epidemics.

In the 21st Century, here where I am in Hong Kong,

authorities closed schools for three weeks

during the peak of the SARS epidemic in 2003,

and, more recently, schools were closed to control

influenza epidemics in 2008 and in 2009.

In March 2008,

at the height of the winter influenza season,

and following three pediatric deaths

associated with influenza,

the government announced that it would close

all nurseries, kindergartens, and primary schools

the following day, for a week.

This would then be followed, immediately,

by the scheduled one week Easter break,

for a total closure period of two consecutive weeks.

We can look at what happened,

and try to make some inferences

about the impact of school closure.

Here we can see the weekly consultation rate

of influenza-like illnesses in Hong Kong,

and the weekly detection rates

of influenza viruses in children and adults.

Infections peaked in mid to late February,

and incidence rates were declining

by the school closure period

that started on the 13th of March.

Rather than try to directly interpret

changes in the epidemic curves,

we used a statistical approach

to estimate the daily reproductive number.

Shown here, the reproductive number

dipped below one just before the peak in incidence,

and was declining throughout early March,

or there was a decline in transmission

during and after the closure period,

this most likely reflects the waning

in the epidemic that would have occurred

regardless of the school closures.

Since the emergence of avian influenza A (H5N1),

the past 10 years have seen intensive preparations

for the next influenza pandemic.

In the early years of the 21st Century,

many plans were based on the potential

for another pandemic like 1918,

stimulated by the severity

of human infections with H5N1.

Many local and national administrations

included school closures in their plans

for the response to a new influenza pandemic,

as part of a broader range of measures

that could be implemented

depending on the local situation

and the estimated severity

of the new pandemic virus.

Those pandemic plans were put to the test in 2009

when swine flu emerged, first in North America,

and rapidly spread around the world.

Within days of the announcement of the identification

of the new H1N1 strain of swine flu,

and its potential to cause a pandemic,

the administration in Hong Kong

announced their plans for responding.

Part of the response would include

school closures for at least two weeks,

once the first non-imported case was identified,

indicating that transmission

was occurring in the local community.

What actually happened is that despite

imported cases being identified

throughout May and early June,

the first non-imported case was not identified

until June the 9th and, on June the 10th,

the announcement was made

that nurseries, kindergartens, and primary schools

would all close for two weeks.

Secondary schools were only closed

if swine flu cases were identified in that school.

Subsequently, the school closures were extended

to the start of summer vacation in mid July,

and lasted for around a month in total.

We examined the impact of the school closures

on the course of the first wave

of pandemic H1N1 in Hong Kong.

We constructed a transmission model

with three age classes:

children less than 12 years of age,

children 13 to 17 years of age,

and adults 18 years of age or older.

In the absence of local data on social contacts,

we used the European data to parameterize

the relative transmissibility

within and between age groups,

and we allowed susceptibility to vary by age.

We then estimated the changes

in the proportion of infections

that were notified over time,

called the reporting rate,

and the change in transmissibility

associated with the school closures

in younger children

and the school vacation in all children.

Here are our results.

We estimated that transmission

within children dropped 70%

during the school closures and summer vacation,

with a reproductive number

of 1.7 before June the 11th,

1.5 between June the 12th and July the 10th,

and 1.1 after July the 10th.

As part of the model,

we estimated that reporting rates began to decline

in mid-June and stopped declining on June the 29th,

with a final reporting rate of 5.2%.

This is very consistent

with a separate serological study,

in which we estimated that 3.9% of infections

were laboratory confirmed.

We also estimated that children were 2.6 times

as susceptible to infection as adults,

consistent with a separate study,

in the United States, in which children

were twice as susceptible to infection.

In conclusion, we demonstrated

that school closures reduced overall transmission

by 25 percent, and delayed the peak in H1N1 incidence

to September, when schools re-opened.

Other studies have demonstrated

significant impact of school closures

in the 2009 pandemic,

while simulation studies have shown

how this type of intervention

can flatten the peak of an epidemic,

reducing both the peak attack rate,

which can help to prevent hospitals

from being overwhelmed, and also reducing

the cumulative incidence of infections.

Having presented the benefits of school closures,

I will finish with a few comments

on the limitations of this intervention.

In many locations in which it is common

for both parents to work,

school closures can cause major disruption

and economic loss to families because of the need

to arrange child care at short notice.

In addition, many children in deprived areas

are reliant on subsidized school meals.

School closures are therefore likely to be considered

only in the most serious situations,

such as severe influenza pandemics.

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