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Table 1 Epidemiologic studies of MERS, 2012–2017

From: MERS transmission and risk factors: a systematic review

Author (year)

Country

Study period

No. of patients

(M/F)

Age of patients

Fatality rate

Contact/ comorbidity

Index related to infectivity

Index related to severity

 Ahmed (2017) [31]

Saudi Arabia

2015–2017

537 (370/167)

55 ± 17.9

218/537 (40.6%)

• Comorbidity: 73.9%

• Contacts

- Hospital-acquired: 38.7%

- Household: 9.9%

- Camel: 25.3%

- Unknown: 26.1%

 

• Onset to confirmation: 4 days (IQR: 2–7 days)

 Alenazi (2017) [12]

Saudi Arabia

2015

130 (66/64)

63.5 (community-acquired), 64.7 (healthcare-acquired), 40.1 (HCW)

51/130 (39.2%)

• Contacts

- Community-acquired: 20%

- Healthcare-acquired: 46.9%

- HCWs: 33.1%

• R

- Hospital-acquired: 0.98 for 2nd, 0.64 for 3rd, 0.23 for 4th generation

 

 El- Bushra (2017) [21]

Saudi Arabia

2015

87

n.r.

n.r.

• Contacts

- 20 primary, 39 first, 18 s, 7 third, 3 fourth generation

• Secondary attack rate/10,000: 42 (95% CI: 33–54)

 

 Kim (2017)

South Korea

2015

186 (111/75)

55

38/186

(19.9%)

• Contacts

- Hospital (99.4%)

- Household (0.6%)

- Community (0%)

• Comorbidity

- 29/38 fatalities had underlying disease

  

 Park (2017) [23]

South Korea

2015

25 (13/12)

71a (IQR: 38–86)

25/11 (44.0%)

 

• Attack rate: 3.7%

• Incubation period: 6.1 days

 

 Sha (2017) [29]

Middle East area/

South Korea

2012–2016

683 (423/260)

50–60 (fatal), 38–46 (non-fatal)

182 (26.6%)

(Middle East: 25.9%,

South Korea: 13.8%)

• Comorbidity

- 67.9% in fatal, 22.2% in nonfatal cases

• Incubation period

- 4.5–5 days in Middle East area

- 6 days in South Korea

• Onset to confirmation

- 8 days in fatal, 4 days in nonfatal in Middle East area

- 4 days in fatal, 5 days nonfatal in South Korea

• Onset to death

- 11.5 days in Middle East area

- 11 days in South Korea

• Onset to discharge

- 14 days in Middle East area

- 17 days in South Korea

 Sherbini (2017) [32]

Saudi Arabia

2014

29 (20/9)

45 ± 12

10 (34%)

• Comorbidities

- Diabetes (31%)

- Chronic kidney disease (27%)

 

• Symptoms to hospitalization: 2.9–5 days

 Assiri (2016) [36]

Saudi Arabia

2014–2015

38 (28/10)

51 (range 17–84)

21/38 (55.3%)

• Contacts

- 13 HCWs

- 15 were associated with 1 dialysis unit

 

• Onset to death/discharge: 17 days (range 1.0–84.0)

 Cho (2016) [5]

South Korea

2015

82 (53/29)

57 (patients and visitors),

38 (HCW)

n.r.

• Contacts

- Patients: 40.2%

- Visitors: 50%

- HCWs: 9.8%

• Comorbidity

- 24 (29%) had underlying disease

• Incubation period: 7 days (range: 2–17, IQR: 5–10)

• Overall attack rate

- Patients in the emergency room: 4% (30/ 675)

- Visitors: 6% (38/683)

 

 Halim (2016) [33]

Saudi Arabia

2016

32 (20/12)

43.99 ± 13.03

14/32 (43.8%)

  

• From symptom to hospitalization

- 5.3 ± 3.3 days

• Total length of stay

- 15 ± 3.6 days

 Liu (2016)

Taiwan

2012–2015

1368 (883/476)a

49 (range: 2–90)

35.6% (487/1368)

• CFR

7.03% for HCW

- 36.96% for non-HCW

• Contacts

- Patients: 46.2%

- Family members or visitors: 34.9%

- HCW: 18.9%

 

• Onset to death

- 13 (4–17) days for HCP

- 12 (1–52) days for non-HCW

• Onset to confirmation

- 6 (1–14) days for HCP

- 10 (1–21) days for non-HCW

 Mohd (2016) [40]

Saudi Arabia

2014–2015

80 (48/32)

40a

• 10% (8/80)

• Comorbidity

- Not different from non-MERS groups

  

 Park (2016) [24]

South Korea

2015

23 (13/10)

66a (range: 31–87) in hospital A;

74.5a (range: 60–82) in hospital B

11/23 (47.8%)

• Generation

- 23 in 2nd; 3 in 3rd

• Incubation period

- 7.8 days (95% CI: 6.0–10.0)

• Serial interval

- 14.6 days (95% CI, 12.9–16.5)

• Secondary attack rate

- 15.8% in hospital A

- 14.3% in hospital B

• Time to deathc

- 12.5 days (IQR: 5.5–19) in hospital A

- 11 days (IQR: 9–16) in hospital B

 Virlogeux (2016) [25]

South Korea

2015

170 (98/72)

54.6 ± 16.2

36/170 (21%)

 

Incubation period: 6.9 days (95% CI: 6.3–7.5)

 

 Chowell (2015) [8]

Saudi Arabia, South Korea

2013–2015

973 MERS and 7634 SARS cases

n.r.

n.r.

• Contacts

- 43.5–100% were linked to healthcare setting in MERS

R0 (95% CI)

- MERS: 0.91 (0.36–1.44)

- SARS: 0.95 (0.67–1.23)

Infection rate of disease among HCWs:

- MERS: 13.4–13.5%

- SARS: 18.8–57.1%

 

 Cowling (2015) [26]

South Korea

2015

166 (101/65)

55.4 (range: 16–87)

24/166 (14.5%)

• Contacts

- 119 cases had contact with a confirmed case

- 30/166 (18%) were healthcare personnel

• Incubation period: 6.7 days

• Serial interval: 12.6 days.

 

 KCDC (2015) [4]

South Korea

2015

186 (111/75)

55a (IQR: 42–66)

36/186 (19.4%)

• Contacts

- 44.1% patients exposed in hospitals

- 32.8% caregivers

- 13.4% HCWs

• Comorbidities

- 45.2%

• Incubation period

- 6.83 days (95% CI: 6.31,7.36)

 

 Ki (2015) [3]

South Korea

2015

186 (111/75)

50s in men and 60s in women

36/186 (19.4%)

• Generation

- 28 in 1st (15.1%); 125 in 2nd (67.2%); 32 in 3rd (17.2%); 2 were not certain

• Contacts

- Same hospital: 82 (44%)

- Family/healthcare aides/visitors: 71 (38%)

- HCWs: 31 (17%)

• Comorbidities

- 77 (41%) had underlying diseases

• Incubation period: 6.5 days (2–16 days).

• From symptom onset to confirmation: 5 days (0–17 days)

• From symptom onset to discharge from the hospital: 20 days (8–41 days).

• From symptom onset to death: 13 days (1–41 days)

 Ministry of Health, South Korea (2016) [27]

South Korea

2015

186 (111/75)

50s (21.6%), 60s (19.9%)

38/186 (20.4%)

• Generation

- 28 in 2nd, 120 in 3rd, 26 in 4th, 11 in unclear/

unknown

• Contacts

- 82 patients in hospital - 63 family members/

visitors

- 39 HCWs

- 2 others

• Incubation period

- 6.83 days (95% CI: 6.31–7.36)

 

 Noorwali (2015) [37]

Saudi Arabia

2014

261 (171/90)

n.r.

110/261 (42%)

• Contacts

- 84 HCWs

- 177 non-HCWs

  

 Park (2015) [28]

South Korea

2015

37 (21/16)

51.7 (range: 24–79)

6/37 (16.2%)

• Generation

- 1 in 1st, 25 in 2nd, 11 in 3rd

• Contacts

- 20 patients

- 12 relatives of patients

- 3 HCWs

- 1 unrelated visitors

• Comorbidities

- 5/6 in fatal, 3/31 in nonfatal

Incubation period

- 6 days (95% CI: 4–7 days)

• Symptom onset to confirmation

- 6.5 days (95% CI: 4–9) for all cases

- 9 days for second cases

- 4 days for third cases

 Drosten (2014) [22]

Saudi Arabia

2013

26 (17/9)

55a (range: 2–83)

18/26 (69.2%)

• Contacts

- 280 household contacts

• Secondary transmission: 4%

 

 Assiri (2013) [7]

Saudi Arabia

2012–2013

47 (36/11)

n.r.

28/47 (60%)

• Comorbidities

- 45 had underlying comorbid medical disorders (96%)

• Incubation period: 5.2 days

 

 Breban (2013) [9]

Multiple areas

2012–2013

64 (44/17) b

56a (IQR 41–68.5)

38/64 (59.4%)

n.r.

• R0: 0.69 (95% CI 0.50–0.92)

 

 Oboho (2012) [38]

Saudi Arabia

2014

255 (174/81)

45a (IQR:30–59)

93 (36.5%)

• Contacts

- 40 of 191 symptomatic were HCWs (20.9%)

 

n.r.

 Penttinen (2013) [41]

Multiple areas

2012–2013

133 (51/77) b

n.r.

45%

• Contacts

- 14 primary cases, 129 cases on transmission

 

• Proportion to ICU:

60 cases (45%)

Estimating the index of infectivity and severity using secondary data

Author (year)

Country

Study period

Indexes related to infectivity

Index related to severity

 Chang (2017) [18]

South Korea

2015

• R0

- 8.097

 

 Choi (2017) [15]

South Korea, Saudi Arabia

2015

• R0

- 3.9 in South Korea

- 1.9–3.9 in Saudi Arabia (1.9 in Riyadh, 3.9 in Jeddah)

 

 Eifan (2017) [13]

Saudi Arabia

2013–2015

• R

- 0.85–0.97

 

 Zhang (2017) [17]

South Korea

2015

• R

- 2.5–7.2

 

 Kim (2016) [16]

South Korea

2015

• R0

- 5.4 (95% CI: 4.61–6.19) in period 1

- 0.14 (95% CI: 0.04–0.26) in period 2

• Infectivity of hospitalized patients

- 22 (95% CI: 18.73–25.27) in period 1

- 1 (95% CI: 0.16–1.84) in period 2

 

 Lessler (2016) [39]

Saudi Arabia

2012–2014

 

• CFR: 22% (95% CI: 18, 25)

 Kucharski (2015) [10]

Multiple areas

2012–2013

• R0: 0.47 (95% CI: 0.29–0.80)

 

 Mizumoto (2015) [35]

South Korea

2015

 

• CFR: 20.0% (95% CI): 14.6, 26.2).

 Xia (2015) [19]

South Korea

2015

• R0

- 4.422 in early stage

- 0.385 with control

from hospitalization to death: 15.16 (0–42) (mean, range)

 Cauche-mez (2014) [6]

Multiple areas

2012–2013

• Incubation period

- 5.5 (95% CI: 3.6–10·2)

• R0: 0.8–1.3

• CFR

- 74% (95% CI: 49–91) for first cases

- 21% (95% CI: 7–42) for second cases

 Chowell (2014) [11]

Saudi Arabia

2013

• R overall

- 0.45 (95% CI: 0.29, 0.61) under the surveillance-bias scenario

- 0.88 (95% CI: 0.58, 1.20) under the differential-transmissibility scenario

 

 Poletto (2014) [14]

Middle East area

2012–2013

• R: 0.50 (95% CI: 0.30–0.77)

 
  1. CI confidence interval, ICU intensive care unit, IQR interquartile range, HCW healthcare worker, SARS severe acute respiratory syndrome
  2. aMedian age, the others are mean age
  3. bInformation of several participants was missing
  4. cDefinition is not clear in this study