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Guideline for the Prevention and Control of Norovirus Gastroenteritis Outbreaks in Healthcare Settings, 2011

GRADE Table Q1 What person, virus or environmental characteristics increase or decrease the risk of norovirus infection in healthcare settings?

Person characteristics

Laboratory characteristics

Comparison Outcome Quantity and type of evidence Findings Starting grade Decrease GRADE Increase GRADE GRADE of Evidence for Outcome Overall GRADE of Evidence Base
S
t
u
d
y
 
Q
u
a
l
i
t
y
**
C
o
n
s
i
s
t
e
n
c
y
**
D
i
r
e
c
t
n
e
s
s
**
P
r
e
c
i
s
i
o
n
**
P
u
b
l
i
c
a
t
i
o
n
 
B
i
a
s
**
L
a
r
g
e
 
M
a
g
n
i
t
u
d
e
**
D
o
s
e
-
r
e
s
p
o
n
s
e
C
o
n
f
o
u
n
d
e
r
s
Antibody levels Symptomatic norovirus/ CaCV infection* 3 OBS 74-76 4/5 volunteers ill with norovirus showed a serum antibody rise in 1 OBS. After a second challenge, a pronounced antibody rise was again detected in these 4 subjects. The fifth ill subject maintained persistently elevated antibody levels at all times 76
 
Pre-existing serum CaCV antibody were a possible protective factor in 1 OBS in a Japanese orphanage 75
 
Uninfected subjects had a lower preexisting antibody titer than infected subjects in 1 OBS. As the antibody titer increased, the incidence of vomiting, nausea, headache/body aches increased 74
Low 0 −1 0 0 0 0 0 0 Very Low Very Low
Secretor genotype Symptomatic norovirus infection* 2 OBS 70,71 FUT2 non-secretor genotype was significantly associated with resistance to nosocomial and sporadic outbreaks of norovirus in 1 OBS 71
 
Presence of secretor positive genotype was associated with an increased risk in 1 OBS among volunteers challenged with norovirus 70
Low 0 0 0 0 0 +2 0 0 High High
Asymptomatic norovirus infection 2 OBS 70,72 Presence of secretor positive genotype was associated with an increased risk in 1 OBS among volunteers challenged with norovirus 70
 
Presence of secretor positive genotype was a possible risk factor in 1 OBS among volunteers challenged with norovirus 72
Low 0 0 0 0 0 +2 0 0 High
ABO phenotype Symptomatic norovirus infection* 5 OBS 69,72,73,77,78 Blood group O was not a risk factor in 1 OBS among volunteers challenged with norovirus 72
 
None of the blood types were risk factors in 2 OBS 69,77, one of which involved nosocomial and sporadic outbreaks 77 and the other involved military units 69
 
Blood group O was a possible protective factor in 1 OBS in the healthcare setting, although selection bias may be present 78
 
Blood group B was a possible protective factor in 1 OBS among volunteers challenged with norovirus 73
Low 0 −1 0 0 0 0 0 0 Very Low Very Low
Asymptomatic norovirus infection 2 OBS 72,73 In 1 OBS among volunteers challenged with norovirus, blood group O was a possible risk factor both overall and among secretor positive patients. Blood group A was a possible protective factor overall, but not after controlling for secretor status 72
 
Presence of a B HBGA (B and AB blood groups combined) was a possible protective factor, as was blood group AB in 1 OBS among volunteers challenged with norovirus. Blood group O was a possible risk factor 73
Low 0 −1 0 0 0 0 0 0 Very LowIn 1 OBS among volunteers challenged with norovirus, blood group O was a possible risk factor both overall and among secretor positive patients. Blood group A was a possible protective factor overall, but not after controlling for secretor status 72 Presence of a B HBGA (B and AB blood groups combined) was a possible protective factor, as was blood group AB in 1 OBS among volunteers challenged with norovirus. Blood group O was a possible risk factor 73

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