SARS Epidemiology for Public Health Action SARS Epidemiology for Public Health Action Aileen J Plant

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Text of SARS Epidemiology for Public Health Action SARS Epidemiology for Public Health Action Aileen J Plant

  • SARS Epidemiology for Public Health Action

    Aileen J Plant

    on behalf of

    The Global Network for SARS Epidemiology With thanks to Angela Merianos, Angus Nicoll and all the

    SARS epidemiology people around the globe!

  • SARS

    A triumph for networks!

  • Today

    Brief description of epidemiology (Who? When? Where? Why? How?)

    Epidemiology for public health action

    Highlight the unknown

    The challenges ahead

  • The initial challenge

    No name No clear-cut clinical diagnosis No test No idea of clinical course No idea of long term implications Not much idea how it spread When does infectiousness start? When does infectiousness finish? Is there any short term immunity? Is there any long term immunity?

  • Notifications of SARS to WHO by week (21 March-13 June, 2003)

    0

    200

    400

    600

    800

    1000

    1200

    1400

    1600

    21 -M

    ar

    28 -M

    ar

    4- Ap

    r

    11 -A

    pr

    18 -A

    pr

    25 -A

    pr

    2- M

    ay

    9- M

    ay

    16 -M

    ay

    23 -M

    ay

    30 -M

    ay

    6- Ju

    n

    13 -J

    un

    Source: www.who.int

    • Incubation period • Infectious period • Case fatality ratios • Reproduction number • Routes of transmission and exposure dose • Sub-clinical infection • Reservoirs eg animals

  • Incubation period – imprecise but reasonably consistent

    0

    2

    4

    6

    8

    10

    12

    14

    16

    18

    Minimum Mean Maximum

    Canada China Hong Kong SAR Singapore Vietnam WHO Europe

  • Transmission evidence

    Asymptomatic Mild symptoms

    Sick

    Infectiousness

    ?

    Recovering

    ?

    X Y YYY X Quality of evidence

  • Case fatality ratios – crude estimates

    0

    5

    10

    15

    20

    11 -A

    pr

    18 -A

    pr

    25 -A

    pr

    2- M

    ay

    9- M

    ay

    16 -M

    ay

    23 -M

    ay

    30 -M

    ay

    6- Ju

    n

    13 -J

    un

    Pe rc

    en ta

    ge

    Vietnam Hong Kong Singapore Canada China Taiwan Province

  • Routes of tranmission

    All the evidence in favour of close contact • Mostly

  • Cumulative percentage of SARS cases by country and time

    0

    20

    40

    60

    80

    100

    28 -F

    eb

    7- M

    ar

    14 -M

    ar

    21 -M

    ar

    28 -M

    ar

    4- Ap

    r

    11 -A

    pr

    18 -A

    pr

    25 -A

    pr

    2- M

    ay

    9- M

    ay

    16 -M

    ay

    23 -M

    ay

    30 -M

    ay

    6- Ju

    n

    13 -J

    un

    Pe rc

    en ta

    ge

    Vietnam Hong Kong Singapore Canada China Taiwan Province

  • Health Care Workers and SARS

    HCW Hong Kong SAR 58%

    (early report – Lee et al)

    Vietnam 53%

    Sick health care workers matter for SARS but they matter far more for the rest of the health system

  • SARS Vietnam: clinical attack rates by occupational risk groups

    Hospital A % Any doctor 16 Any nurse 35 Administration staff 2 Other staff with patient contact 53 Outside staff 0 Total hospital 18

    Concurrent patients NOT 7 admitted for SARS

    Hospital B 0

    Contacts of one well-tracked 6 (and friendly!) case

  • Conclusions – the challenges ahead

    • clinical diagnostic skills • laboratory capacity • surveillance capacity • response capacity • plans of action • infection control • applied research capacity

    MUST have sufficient:

  • Conclusions

    There is a lot of epidemiological work to be done

    But the good news is

    We don’t have to wait for perfect answers to control SARS, we can

    do it now!

  • Photo: Dr Joel Montgomery, WHO SARS Team, Vietnam

  • Mean age and SARS

    Hong Kong SAR 39.3 (n = 156, Lee et al)

    Hong Kong SAR 39.8 (n = 75, Peiris et al) (Amoy Gardens)

    Vietnam 40.8 (n = 62, unpub)

  • SARS Vietnam: Feb-Mar 2003 No of cases by date of onset – the incubation period

    0

    1

    2

    3

    4

    5

    6

    7

    8

    9

    10

    Fe b

    22

    Fe b

    24

    Fe b

    26

    Fe b

    28

    M ar

    2

    M ar

    4

    M ar

    6

    M ar

    8

    M ar

    1 0

    M ar

    1 2

    M ar

    1 4

    M ar

    1 6

    M ar

    1 8

    M ar

    2 0

    M ar

    2 2

    M ar

    2 4

    M ar

    2 6

    M ar

    2 8

    M ar

    3 0

    Ap r 1

    Ap r 3

    Ap r 5

    Ap r 7

    N o

    of c

    as es

    Index case admitted

    Maximum-minimum incubation period (5 days)

    Median IP (6-7 days)

    Max IP (10 days)

  • Infection control - it matters!

    0

    2

    4

    6

    8

    10

    Fe b

    22

    Fe b

    24

    Fe b

    26

    Fe b

    28

    M ar

    2

    M ar

    4

    M ar

    6

    M ar

    8

    M ar

    10

    M ar

    1 2

    M ar

    1 4

    M ar

    1 6

    M ar

    1 8

    M ar

    2 0

    M ar

    2 2

    M ar

    2 4

    M ar

    2 6

    M ar

    2 8

    M ar

    3 0

    Ap r 1

    Ap r 3

    Ap r 5

    Ap r 7

    N um

    be r o

    f c as

    es

    HCW Other

    Infection control strengthened

    Floor of hospital isolated

    No of cases by date of onset of symptoms, Vietnam

    Maximum incubation period