epidemiology of varicella zoster virus infections in
TRANSCRIPT
12-Jul-17
1
Epidemiology of varicella
zoster virus infections in
Australia, 1998-2015
Meru Sheel, Helen Quinn, Frank Beard, Aditi Dey, Martyn Kirk,
Kristine Macartney
MAE Scholar
National Centre for Immunisation Research and Surveillance
National Centre for Epidemiology and population Health,
Australian National University
Varicella (chicken pox)
• Primary infection with varicella
zoster virus (VZV)
• Acute and self-limiting
• Severe complications
• November 2005, vaccine
funded under the National
Immunisation Program (NIP)
• Children aged 18 months
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Herpes zoster (shingles)
• Reactivation of latent VZV
• Rash accompanied with acute pain
• Severe complications: Post-herpetic neuralgia (PHN)
• November 2016, vaccine funded under the NIP
• Adults aged 70-79 years
Study Aims
• Epidemiological review of varicella and herpes
zoster
• Baseline for herpes zoster
• Assess the impact of the national varicella
immunisation program
• Varicella
• Herpes zoster (HZ)
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Data sources
National Notifiable Diseases Surveillance System (NNDSS)
2002-2015
National Mortality Database & Causes of Death Data, Australian
Coordinating Registry and Australian Bureau of Statistics
1998-2013
Mid-year population estimates from the Australian Bureau of Statistics
National Hospital Morbidity Database maintained by the Australian Institute of
Health and Welfare1999-2013
ICD-10-AMVaricella: B01.0- B01.9
HZ: B02.0- B02.9PHN: B022, G530, G531
Analyses
• Rates per 100,000
• Notifications
• Hospitalisations
• Principal diagnoses
• Negative binomial regression
• Pre-varicella vaccine (1999-2004) versus post-varicella
vaccine (2007-2013)
• Indigenous status
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VZV notifications, Australia, 2002-2015
Chickenpox ShinglesUnspecified
VZV notifications, Australia, 2002-2015
Chickenpox ShinglesUnspecified
N/A
C 7.1%S 3.8%U 89.1%
C 41.9%S 56.4%U 1.8%
C 24.1%S 66.3%U 9.7%
C 17.1%S 38.9%U 44%
C 12.7%S 26.5%U 60.7%
C 11.4%S 63.8%U 24.8%C 13.2%
S 19.8%U 66.9%
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Varicella notification rates, SA, 2002-2015
0
50
100
150
200
250
300
350
400
450
200
2
200
3
200
4
200
5
200
6
200
7
200
8
200
9
201
0
201
1
201
2
201
3
201
4
201
5
No
tifi
cati
on
s p
er
10
0,0
00
Year of notification
0-4 years
5-9 years
10-14 years
15-19 years
20-29 years
30-39 years
≥40 years
Vaccine funded
Varicella hospitalisation rates, Australia, 1999-2013
0
10
20
30
40
50
60
19
99
20
00
20
01
20
02
20
03
20
04
20
05
20
06
20
07
20
08
20
09
20
10
20
11
20
12
20
13
Ho
spit
alis
atio
ns
pe
r 1
00
,00
0
Year
0-17 months18-59 months5-9 years10-14 years15-19 years20-29 years30-39 years≥40 years
Vaccine funded
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Impact of national varicella immunisation, Australia
0
10
20
30
40
50
60
0-17 mo 18-59 mo
Ho
sp
italisati
on
s p
er
100,0
00
Age groups
Pre-vaccine Post-vaccine
84%
Herd effects of varicella immunisation, Australia
0
10
20
30
40
50
60
0-17 mo 18-59 mo
Ho
sp
italisati
on
s p
er
100,0
00
Age groups
Pre-vaccine Post-vaccine
84%67%
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7
0
0.5
1
1.5
2
2.5
3
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Inci
de
nce
rat
e r
atio
*
Age groups
pre-varicella vaccine
post-varicella vaccine
0-17 months 18-59 months All ages
Varicella in Indigenous Australians, 2002-2013#
#QLD, WA, NT and SA* Indigenous vs non-Indigenous people
Varicella mortality, Australia, 1998-2013
• In persons aged <10 years
• 1998-2004: 6 deaths
• 2007-2013: <4 deaths
• In persons aged ≤40 years
• 1998-2004: 15 deaths
• 2007-2013: 5 deaths
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HZ notification rates, SA, 2002-2015
0
50
100
150
200
250
300
350
400
20
02
20
03
20
04
20
05
20
06
20
07
20
08
20
09
20
10
20
11
20
12
20
13
20
14
20
15
No
tifi
cati
on
s p
er
10
0,0
00
Year of notification
0-49 years
50-59 years
60-69 years
70-79 years
≥80 years
HZ & PHN hospitalisations, Australia, 1999-2013
0
10
20
30
40
50
60
70
80
90
100
19
99
20
00
20
01
20
02
20
03
20
04
20
05
20
06
20
07
20
08
20
09
20
10
20
11
20
12
20
13
Ho
spit
alis
atio
ns
pe
r 1
00
,00
00
Year
PHN 70-74 years PHN ≥75 years PHN all ages
HZ 70-74 years HZ ≥75 years HZ all ages
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Conclusions
• Varicella
• Reduced incidence
• Hospitalisations reduced by 84% in children aged 18-59
months
• ‘Plateaued’ hospitalisation rates
• ~ 300 hospitalisations in <40 year age group
• Herpes zoster
• Increased notifications
• Lack of useful data for monitoring disease epidemiology
and vaccine impact
Recommendations
• Establish robust surveillance for varicella, herpes
zoster and post-herpetic neuralgia
• Re-examine NIP funding of a 2nd dose of varicella
vaccine
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Acknowledgements
• Peter McIntyre, NCIRS
• Ann Koehler, South Australia Health
• Peter Markey, Department of Health, Northern Territory
• Allison Cairns, Commonwealth Department of Health
• NCIRS & MAE colleagues
• Australian Coordinating Registry, state and territory registries of births, deaths
and marriages, state and territory coroners, and the National Coronial
Information System
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Data Limitations
• Time lag in receiving administrative datasets
• Limited baseline data
• Poor reporting through the NNDSS
• Limited age-specific data for Indigenous
populations
• Incomplete Indigenous status for earlier years
• Only 3% cases of HZ are hospitalised
Varicella vaccine coverage, Australia, 2006-2015
0
10
20
30
40
50
60
70
80
90
100
30
Sep
06
31
Mar
07
30
Sep
07
31
Mar
08
30
Sep
08
31
Mar
09
30
Sep
09
31
Mar
10
30
Sep
10
31
Mar
11
30
Sep
11
31
Mar
12
30
Sep
12
31
Mar
13
30
Sep
13
31
Mar
14
30
Sep
14
31
Mar
15
30
Sep
15
Var
ice
lla v
acci
ne
co
vera
ge (
%)
Coverage assessment date
MMR-V
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Varicella-related hospitalisations, Australia 1999-
2013
0
2
4
6
8
10
12
19
99
20
00
20
01
20
02
20
03
20
04
20
05
20
06
20
07
20
08
20
09
20
10
20
11
20
12
20
13
Ho
spit
ali
sati
on
s p
er
10
0,0
00
po
pu
lati
on
Year of admission
Principal diagonses All diagnoses
Varicella vaccinefundedPre-vaccine Post-vaccine
Reduced hospitalisation in children less than 10
years of age
Pre-vaccine
(1999-2004)
Post-vaccine
(2005-2013)
Post-vaccine/ pre-
vaccine
Age group Rate per 100,000
(95% CI)
Rate per 100,000
(95% CI)
IRR
(95% CI)
0-17 months 45.2
(41.6-549.1)
14.8
(12.1-18.1)
0.33
(0.26-0.40)
18-59 months 40.7
(35.1-47.2)
6.7
(5.0-8.9)
0.16
(0.12-0.23)
5-9 years 8.9
(7.82-10.2)
3.6
(2.5-5.0)
0.40
(0.27-0.58)
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Impact of national varicella immunisation
program on HZ hospitalisations*
Principal HZ Pre-vaccine
(1999-2004)
Post-vaccine
(2005-2013)
Post-vaccine/ pre-
vaccine
Age group Rate per 100,000
(95% CI)
Rate per 100,000
(95% CI)
IRR
(95% CI)
70-74 years 37.4
(35.8-39.0)
38.2
(36.3-40.2)
0.94
(0.88-1.02)
75-79 years 59.4
(57.4-61.6)
62.7
(60.0-65.6)
0.89
(0.84-0.95)
*Non-Aboriginal and Torres Strait Islander populations only