SARS Epidemiology for Public Health Action · SARS Epidemiology for Public Health Action Aileen J Plant on behalf of The Global Network for SARS Epidemiology With thanks to Angela
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SARS Epidemiology for Public Health Action
Aileen J Plant
on behalf of
The Global Network for SARS EpidemiologyWith 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 diagnosisNo testNo idea of clinical courseNo idea of long term implicationsNot much idea how it spreadWhen 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
CanadaChinaHong Kong SARSingaporeVietnamWHO Europe
Transmission evidence
Asymptomatic Mild symptoms
Sick
Infectiousness
?
Recovering
?
X Y YYY XQuality 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
Perc
enta
ge
Vietnam Hong Kong SingaporeCanada China Taiwan Province
Routes of tranmission
All the evidence in favour of close contact • Mostly <1 metre• Fomites can not be excluded – BUT –not much evidence of prolonged risk in spite of microbiological findings• Aerosol is not likely• Amoy Gardens ???
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
Perc
enta
ge
VietnamHong KongSingaporeCanadaChinaTaiwan Province
Health Care Workers and SARS
HCWHong 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 16Any nurse 35Administration staff 2Other staff with patient contact 53Outside staff 0Total hospital 18
Concurrent patients NOT 7admitted 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 2003No of cases by date of onset – the incubation period
0
1
2
3
4
5
6
7
8
9
10
Feb
22
Feb
24
Feb
26
Feb
28
Mar
2
Mar
4
Mar
6
Mar
8
Mar
10
Mar
12
Mar
14
Mar
16
Mar
18
Mar
20
Mar
22
Mar
24
Mar
26
Mar
28
Mar
30
Apr 1
Apr 3
Apr 5
Apr 7
No
of c
ases
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
Feb
22
Feb
24
Feb
26
Feb
28
Mar
2
Mar
4
Mar
6
Mar
8
Mar
10
Mar
12
Mar
14
Mar
16
Mar
18
Mar
20
Mar
22
Mar
24
Mar
26
Mar
28
Mar
30
Apr 1
Apr 3
Apr 5
Apr 7
Num
ber o
f cas
es
HCW Other
Infection control strengthened
Floor of hospital isolated
No of cases by date of onset of symptoms, Vietnam
Maximum incubation period
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