Communicability Patient factors

Not infectious prior to symptoms Increases with increased severity of disease Increases post-onset symptoms (peak at day

7-10) Not infectious after recover No evidence of prolonged carriage or relapse

Setting Duration, degree of contact Contact with airway (?contact with stool)

Communicability: time in disease course

Peiris et al. Lancet, 2003

NPA / TNS N=392

Onset (days)

0 – 23 – 56 – 8

9 – 1112 – 1415 – 1718 – 2021 – 23

% positive

3143605759351813

PCR: Time to positive

%positive

0578690

100336043

Stools N=50

Public Health - Hong Kong May 2003

Communicability Patient factors

Not infectious prior to symptoms Increases with increased severity of disease Increases post-onset symptoms (peak at day

7-10) Not infectious after recover No evidence of prolonged carriage or relapse

Setting Duration, degree of contact Contact with airway (?contact with stool)

Exposure Risk in ICU Loeb et al. (ICAAC 2003)

8/32 entering room vs 0/11 others (P=0.09) Risks: assisting with intubation RR=4.2 (1.6, 11) suctioning prior to intubation RR=4.2 (1.6,11) manipulation O2 mask RR=9.0 (1.3,65)

• Scales et al. (ICAAC 2003)- 6/31 entering room vs. 1/38 others RR=8.8 (1,420)- Risks: in room for >4 hrs RR=24 (1.2,311) present >30min with NIV RR=105 (3,3000)

SARS Control

Identification of cases Isolation/quarantine

IP

Varia et al. CMAJ 2003

Toronto Area Probable and Suspect cases by source of infectionMay 5, 2003

0

2

4

6

8

10

1223

-Feb

-03

25-F

eb-0

327

-Feb

-03

01-M

ar-0

303

-Mar

-03

05-M

ar-0

307

-Mar

-03

09-M

ar-0

311

-Mar

-03

13-M

ar-0

315

-Mar

-03

17-M

ar-0

319

-Mar

-03

21-M

ar-0

323

-Mar

-03

25-M

ar-0

327

-Mar

-03

29-M

ar-0

331

-Mar

-03

02-A

pr-0

304

-Apr

-03

06-A

pr-0

308

-Apr

-03

10-A

pr-0

312

-Apr

-03

14-A

pr-0

316

-Apr

-03

18-A

pr-0

320

-Apr

-03

22-A

pr-0

324

-Apr

-03

26-A

pr-0

328

-Apr

-03

30-A

pr-0

302

-May

-03

04-M

ay-0

3

Date of onset of first symptoms

Nu

mb

er

of

ca

se

s (

P &

S)

Travel

Non health care

Health care settings

PPP

ATM

Outpatient

Entrance

Drug Store Emergency

EntranceSecurity Emergency

Registration

Emergency

Nurse

Admitting

Vending

Machines

Waiting Room

Trauma

Room

Room 1

Room 2

Room 3

Room 4

Room 5

Room 6

Stock

Room

Room 7

Room 8

Room 9

Eye Room

Fracture

Room

Soiled

Linen

Show er

W CW C

Observation Room

Nursing Station

Ante

Room

Bed 1

Bed 2

Bed 3

Bed 4

Bed 5

Bed 6

Bed 1 Bed 2 Bed 3

Bed 4 Bed 5

Bed 8 Bed 7 Bed 6

Bed 1

Bed 2Bed3

Grace DivisionEmergency DepartmentMarch 16; 22:45-23:30

Reported cases of SARS in cases linked to the BLD group

March 20 to April 16, 2003

0

1

2

3

4

5

6

7

8

19/0

3/03

21/0

3/03

23/0

3/03

25/0

3/03

27/0

3/03

29/0

3/03

31/0

3/03

02/0

4/03

04/0

4/03

06/0

4/03

08/0

4/03

10/0

4/03

12/0

4/03

14/0

4/03

16/0

4/03

Date of onset of symptoms

Nu

mb

er

of

ca

se

s

Health Care WorkerBLD

Family

Mr. S Jr.

Church meetings Funeral

Cluster of SARS in HCWs 54 y.o.m. physician

April 1-2 saw 3 patients from BLD community

April 4-5 became ill April 12 admitted to ICU

April 13 Intubated RT-PCR positive in sputum and stool

April 15-21 9 HCW become ill including 6 involved with

intubationMMWR 2003 May 16

0

2

4

6

8

10

12

April May June

Household

Hospital

Effectiveness of Precautions

Seto et al. Lancet 2003: Case (n=13)/Control (241) Lower risk with handwashing OR 0.2 (.07,1) Lower risk with gloves OR 0.5 (.14,1.6) Lower risk with gown OR undef

(P=.006) Lower with masks OR 0.08 (.02,.33)

Loeb et al. ICAAC 2003: Cohort (43 nurses, 8 infected) Lower risk with gloves OR 0.45 (.44,

4.5) Lower risk with gown OR 0.36 (.10,1.2) Lower risk with masks OR 0.23 (.07,.78)

Number of SARs hospitalization days Mount Sinai Hospital

0

2

4

6

8

10

12

14

16

18

Num

ber

of c

ases

338 days of protected exposure(?1 staff infected)

MarchAprilMarch

31 hours of unprotected exposure(7 staff infected)

Transmission in the setting of any precautions, Toronto

Phase I - 260 patients 22 HCW infected intubation, cardiac arrest, “pre-intubation”

care

Phase II – 129 patients 3 HCW infected cardiac arrest, bronchoscopy, “pre-

intubation” care

Differences between Phase I and Phase II

HCW training and awareness “Enhancements”

Double gloves, hair & foot covering, greens

Practice issues Minimize time in room Minimize contact with patient Medical therapy to reduce cough/vomiting Minimize procedures that increase risk of

droplets

Protective Barriers: N95 masks, face shields, gown and gloves

Phase II

What went wrong?

NYGH-4W- June 6

0

1

2

3

4

5

6

7

4PT

4WHCWRelaxation of precautions

Impact on NYGH

HCWs 39 Patients 30 Visitors 18

Conclusions

Disease driven by exposure Transmission

Primarily in health care settings Droplet/contact Heterogeneous between patients

Control Unrecognized patients are the most

important problem Precautions include not only barriers, but

also practice Compliance with precautions is critical

Acknowledgements

Allison McGeer and Karen GreenThe staff and patients of greater Toronto area hospitals and public health departments