Nonpharmacological interventions before a human influenza pandemic

1
Non-pharmacological interventions before a human
influenza pandemic

• Dr. Mónica Guardo
• Pan American Health Organization - PAHO
• Bogotá April 20, 2006

2
Aspects Covered

• Definition non-pharmacological interventions
• Characteristics of the transmission of influenza
• Review of the theoretical foundations of
  interventions to control the spread from one
  country to another
• Theoretical foundation of the measures to reduce
  transmission within each country, at a national
  and community level
• Past evidence, of the present and mathematical
  models
• Measures to reduce individual risk
• Recommendations and discussion

3
Non-Pharmacological Interventions

• Use of pharmacological measures against a
  pandemic
• Vaccines and anti viral medicines
• Availability will not be enough
• 2005 World Health Organization (WHO)
• Non-pharmacological public health interventions
  recommended for the updated preparation plan
• 2006 Experts Committee
• Emerging Infectious Diseases, Vol.12 (1)
  January 2006, pg 81-94
• www.cdc.gov/eid
• Definition
• Interventions designed to reduce exposure in the
  people susceptible to an infectious agent

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Non-Pharmacological Interventions Fundamental
Concepts

• Measures to limit international spread
• Filtering and travel restrictions
• Measures to limit national and local spread
• Isolation and treatment of the sick
• Vigilance and quarantine of those exposed
• Social distancing measures (like cancellation of
  reunions and closing of schools)
• Measures to limit individual risk
• Washing hands
• Use of masks in public
• Public communication of risks

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Excretion and Viral Transmission

• Symptomatic
• adults - viral elimination 24-48 hours before
  symptoms
• Maximum infectiousness 24-72 hours of the disease
  until day 5
• Symptomatic children faster viral elimination
  and for a longer period
• Asymptomatic related to a group of adults in
  New Zealand, 1991
• 26 adults that packed fertilizer during 8 hours
• 16 with influenza type disease
• Initial case malaise, without respiratory
  symptoms
• Influenza type disease six hours after finishing
  work
• Transmission by infected persons in an incubation
  period or those that show an asymptomatic
  infection

Sheat K. An investigation into an explosive
outbreak of influenza - New Plymouth. Communicable
Disease New Zealand 1992 9218-19.
6
Forms of Transmission
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Forms of Transmission

• Transmission person to person
• Drops (particles gt5µm in diameter) cough or
  sneeze
• Replication in epithelial cells of the
  respiratory ducts
• Other forms of transmission
• Propagation through aerosol specially with a lack
  of ventilation
• By contact contaminated hands, other surfaces
  or fomites
• Outbreak in a geriatric home in Hawaii
• Transmission of oral secretions from one patient
  to another through a professional without gloves
• Environmental survival of influenza A
• Hard non porous surfaces (steel and plastic) up
  to 24-48 hours
• Clothing, paper, fabric up to 8 12 hours
  (35-40 humidity and 28ºC)
• Major humidity ? less viral survival
• Virus in non porous surfaces passes to the
  hands for up to 24 hours
• Virus in fabrics passes to the hand up to 15
  minutes

Moser MR et al. An outbreak of influenza aboard a
commercial airliner. Am J Epidemiol
19791101-6. Alford RH et al. Human influenza
resulting from aerosol inhalation. Proc Soc Exp
Biol Med 1966122(3)800-4.
Morens DM, Rash VM. Lessons from a nursing home
outbreak of influenza A. Infect Control Hosp
Epidemiol 199516(5)275-80.
Bean B et al. Survival of influenza viruses on
environmental surfaces. J Infect Dis
1982146(1)47-51.
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Incubation and Viral Infectiousness

• Short period of incubation - 2 days (between 1 to
  4 days)
• Symptoms 1-4 days post exposure
• Intervals between successive cases between the
  appearance of the disease in two successive
  patients in the transmission chain (2 to 4 days)
• Viral excretion peak (maximum infectiousness)
  initiation of the disease
• SARS comparison
• Interval between successive cases 8 10 days
• Maximum infectiousness the second week of the
  disease
• Greatest time to implement isolation and
  quarantine measures
• Basic reproductive number (Ro)
• Measure of secondary cases generated by an
  infected person (in a totally susceptible
  population)
• 1918 Influenza (R0 1,8 a 3)
• Similar to SARS coronavirus (Ro 2-4)

9
Non-Pharmacological Interventions

• International level
• National and local level
• Community level

10
Experiences from the Influenza Pandemic - 1918
11
Experiences from previous pandemicsPromulgated
quarantine by islands

• October 1918, Australia
• Quarantine in ships, with variable times
• Taking into consideration the date in which the
  most recent case appeared
• 7 days in ships in New Zealand and South Africa,
  independent of cases
• Taking of temperature at least once a day
• Mouth temp 37,2ºC hospital isolation for
  observation
• October 1918 - May 1919
• 79 infected vessels
• 2.795 patients, 48.072 passengers and 10.456 crew
  members
• 149 non infected vessels
• 7.075 passengers and 7.941 crew members
• Without direct evidence of propagation from the
  vessel to the coast
• Notification of the pandemics arrival in
  Australia in January 1919
• Maritime quarantines delayed the entrance of
  influenza by 3 months

• Cumpston JHL. Influenza and maritime quarantine
  in Australia.
• Melbourne Commonwealth of Australia. Quarantine
  Service. Service publication 1919. Report No.
  No. 18.
• McQueen H. "Spanish 'flu",1919 political,
  medical and social aspects. Med J Aust
  19751(18)565-70.

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Effects and doubts about the quarantine in
Australia, 1918

• Possible viral introduction before establishing
  quarantine
• It could not be demonstrated
• Hiding of the disease by officials and soldiers
  of the marine that were returning to Australia in
  European vessels
• To avoid prolonged quarantine
• Infection in Australia
• The mortality rates were less than those of other
  places previously affected

13
Experiences of previous pandemicsOther
quarantine experiences

• African continent - 1918
• Quarantine in three port areas like Liberia,
  Gabón y Ghana
• Delay of entrance by several weeks, but less
  successful than in the islands
• Disease arrived through interior routes
• Canada
• Drastic measures
• Police control points
• Interruption of road and train traffic
• They did not prevent or delay propagation among
  the provinces

14
Effect of quarantine in international frontiers
1957 pandemic

• Israel
• Delayed two months in comparison to neighboring
  countries
• Attributed to the absence of international travel
  with neighboring countries (due to political
  reasons, not quarantine).
• South Africa
• Maritime restrictions resulted in some delay
• No effect in other areas
• Measures have to be severe in order for them to
  be efficient

15
SARS Experiences - 2003
Photo Gavin Joynt
Photo Gavin Joynt
16
Filtering the entrance of travelers arriving via
air SARS, 2003

• 4 countries in Asia and Canada
• Mechanisms for the measurement of body
  temperature
• 35 million travelers, detection 0 cases
• Health Questionnaire
• Travelers supplied information about their
  health, symptoms and exposure history
• 45 million travelers, detection of 4 cases
• Distribution of sanitary warning signs
• 31 million signs distributed to incoming
  travelers, limited information about the follow
  up of those same ones

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Filtering the entrance of travelers arriving via
air SARS, 2003

• Continental China
• Distribution of 450,000 signs
• Detection of 4 SARS cases possibly related to the
  signs
• Thailand
• Distribution of 1 million signs
• Detection of 24 cases with direct relation to
  said signs
• Canada
• 5 people with SARS entered the country none
  presented signs or symptoms at the international
  airports
• Filtering entrance, not a lot of sensibility and
  it was not cost -effective
• Vigilance is preferable for the fast detection of
  imported casesb

aBell DM. WHO Working Group on prevention of
international and community transmission of SARS.
Public health interventions and SARS spread,
2003. Emerg Infect Dis 2004101900-1906.
bSt John RK et al. Border screening for SARS.
Emerg Infect Dis 200511(1)6-10.
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Screening/Filtering passengers exiting via air
SARS, 2003

• March 27, 2003 Recommendation - WHO
• Exit filter for international passengers exiting
  via affected routes
• Transmission of SARS via air travel was not
  documented from countries that implemented exit
  filters
• Reflection of the dissuasive effect on travelers
  and/or a low incidence of SARS?
• Data combined from various countries indicated
• Detection of 1 case per 1.8 million exiting
  passengers that answered the health questionnaire
• None, in the 7 million cases that subjected
  themselves to temperature detection at the time
  of exit

Bell DM. WHO Working Group on prevention of
international and community transmission of SARS.
Public health interventions and SARS spread,
2003. Emerg Infect Dis 2004101900-1906.
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Estimate of the effect of screening/filtering
entrance of travelers entering the United Kingdom

• Mathematical modeling
• Considering filtering exit from countries with
  influenza pandemic
• 9 of asymptomatic persons would show signs
  during their trip to the UK at exit
• greater if duration of flight greater
• 17 (12-23) in travelers from Asian cities
• 12, 000 airplane seats arriving from the Extreme
  Orient to the United Kingdom daily
• 83 of those infected would not be detected
• Travelers arriving through connecting flights are
  not considered

Pitman RJ et al. Entry screening for SARS or
influenza, policy evaluation. Br Med J 2005
http//bmj.bmjjournals.com/cgi/rapidpdf/bmj.38573.
696100.3A
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Recommendations from the WHO to contain
international transmission

• Alert travelers that arrive in the country
• Description of the symptoms and indications of
  where they should inform if they suffer from
  these symptoms
• Consider filtering at exit
• Health declaration and taking of temperature of
  international passengers exiting the affected
  areas during phases 4 and 5
• Consider filtering arrival only when
• Exit filtering at boarding is below optimal
• Islands or geographically isolated areas
• Where the countrys internal vigilance capacity
  is limited

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Advantages and disadvantages of exit filters

• Advantages
• Smaller number of persons filtered
• Greater number of positive prediction values
• Reduction of transmission in flights and ships
• Disadvantages
• Costly and problematic
• It will not be totally efficient since the virus
  can be transmitted by asymptomatic persons that
  will not be detected during the filter
• It is not recommended, during any phase, that
  countries quarantine themselves or that they
  close international frontiers.
• As it happened with SARS, non-pharmacological
  interventions centered principally at a national
  and community level and NOT international
  frontiers.

22
Recommendations for Travelers to H5N1 epizootic
areasPhase 3 Pandemic Alert

• Avoid
• Contact with farms
• Contact with live animals in markets
• Contact with surfaces that appear to be
  contaminated with the fecal matter of chickens or
  other animals
• Diet
• Avoid local food prepared raw, with birds or
  their products
• Only eat birds or their products that have been
  properly cooked
• There are no recommendations for travel
  restrictions to affected countries

23
Non-Pharmacological Interventions

• International level
• National and local level
• Community level

24
Isolation of cases and contact quarantine - 1918

• Notification and obligatory isolation of cases in
  the community
• They did not stop viral transmission and it was
  not very practical
• Canada, Alberta
• Forced domiciliary isolation of cases signs
  indicating quarantine
• They only detected 60 of the cases in the
  community
• Difficulties diagnosing mild cases
• Failure in the notification of cases to the
  authorities
• Australia, New South Wales
• Obligatory notification useful for identifying
  the first cases in a community
• No posterior value
• Military bases and university dorms in 1918
• It did not stop the transmission but seemed to
  reduce the attack rates
• Especially if they were complemented with travel
  restrictions to and from the surrounding community

25
Isolation of cases and quarantine lesions of
SARS, 2003

• Success of public campaigns for
• Self recognition of the disease
• Telephone consultation services with health
  information
• Early isolation of patients seeking medical
  attention
• Inefficient Measures
• Taking temperature of interurban travelers
• Efficient Measures
• Isolation and quarantine in the community
• Measures would be less effective before an
  influenza pandemic

26
Social Distancing Measures

• Avoid crowds
• To reduce the infectious peak of the epidemic,
  prolonged for several weeks
• 1957 Pandemic initially attacked military units,
  schools and other groups in close contact
• Incidence reduced in rural areas
• Closing of schools and daycare centers
• In the Northern hemisphere the reinitiating of
  school activities after summer vacations
• It was important for initiating the main epidemic
  period
• Influenza epidemics are amplified in primary
  schools
• However there is no evidence of the effectiveness
  of closing schools
• Epidemic in Israel, 2000
• Teachers strike ? important reduction in the
  infection rates
• Reinitiating of activities ? increased the rates

27
Simultaneous use of several strategiesHong Kong,
SARS 2003

• Reduction of influenza and other respiratory
  diseases
• Intervention
• Closing of schools, pools and other crowded areas
• Cancellation of sporting events
• Disinfecting taxis, buses and public areas
• Use of masks in public and frequent washing of
  hands
• Less social contact
• Use of masks in public - 76 of residents
• With multiple measures
• There is no certainty of the contribution of the
  use of masks, if there was one1
• Studies carried out of control cases in Beijing
  and Hong Kong during SARS, 20032
• Use of masks in public was independently
  associated with protection towards SARS
• Dosis-response effect3

• Lo JYC et al. Emerg Infect Dis 2005111738-41.
• Wu J et al. Emerg Infect Dis 200410(2)210-6.
• Lau JT et al. Emerg Infect Dis 200410(4)587-92.

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Interim WHO RecommendationsPhases 4 and 5

• Fast detection and isolation of infected persons
• Detection of close contacts during the first 2
  weeks of the disease
• Voluntary quarantine of those with symptoms
  during 1 week
• Use of antiviral medications for the treatment of
  cases and prophylaxis of other people in the
  initially affected area
• Entrance and exit restrictions for people in the
  area initially affected area in the country

29
Interim WHO RecommendationsPhase 6 without
affecting other countries

• Guidance for the sick remain at home as soon as
  symptoms appear
• Warn caretakers adequate precautions
• Non essential national trips to the affected
  areas must be postponed
• If there are still significant areas in the
  country that have not been affected
• People that have been knowingly exposed in a
  plane or large cruise ship
• Consider daily fever controls between passengers
  and crew members
• Consider antiviral prophylactic treatment, if
  available

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Interim WHO RecommendationsPhase 6 pandemic,
all affected countries

• Interruption of patient isolation, detection and
  quarantine of contacts
• These measures will no longer be viable or useful
• Consider social distancing measures in the
  affected communities
• Repeatedly inform the population
• Respect the need to wash hands frequently with
  soap and water
• Respect the need for respiratory hygiene
• Use of masks for the general population
• Must not have noticeable repercussions over the
  transmission
• Must be allowed, since its occurrence is likely
  to be spontaneous

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What can we doas individuals? Interim WHO
recommendations

• Diminishing the transmission of influenza
• Wash hands
• Use masks based on risk
• Avoid contact of hands with nose and mouth and
  take care when coughing and sneezing
• Do not go to work while sick
• Use of masks during close contact with sick
  individuals
• Disinfect domestic surfaces contaminated with
  secretions
• Allow the systematic use of masks in public
  places, without promoting it
• Possible instructions for the use of masks in
  crowded places (public transportation)
• Without evidence support general disinfection of
  the environment/air
• Diminish the transmission of the bird flu A
  (H5N1)
• Avoid contact with dead or sick birds
• Diminish the transmission of human influenza
• Annual vaccine with the anti-influenza vaccine

32
Discarding of chickens potentially infected with
H5N1 without protection Thailand, February 2004
Photo CDC
33
Guidance Washing Hands
Fonte OMS
34
Guidance for patients with a cough

• Respiratory hygiene and etiquette when coughing
• Cover your mouth when you cough and sneeze, avoid
  spitting
• Use handkerchiefs
• Meticulously dispose of handkerchiefs
• Wash hands after contact with respiratory
  secretions
• Sit at least 1 meters distance from other
  patients
• Provide the patient
• Handkerchiefs
• Garbage cans that work without the use of hands
• Water, soap and alcohol
• Disposable towels to dry hands