Impact of Testing Strategies
to Reduce Transmission Risk
for HBV
Ravi Reddy, M Vermeulen
South African National Blood Service (SANBS)
29 July 2013
Overview of SANBS
HQ in
Johannesburg
• SANBS is a private not for profit company operating on
a fee for service basis
• Provides a vein to vein blood transfusion service in 8 of
the 9 provinces in SA.
– WPBTS in Western Cape
• 807,000 units of blood collected annually (100%
voluntary) – 2 800 units bled daily
• 2 testing centres - Johannesburg and Durban
– Also test for Namibia BTS (ID-NAT as well)
• 7 blood processing centres
• 82 blood banks serving > 600 hospitals and clinics.
• SANBS is accredited with the South African National
Accreditation System (SANAS)
– Specific laboratories are ISO 17025 accredited
Donation Testing Strategy
• Quality assured testing of each donation
– EQAS and internal QC systems in place
• Serology is mandatory
– Anti-HIV-1,2, anti-HCV, HBsAg
– Quality assured testing with sensitive serology assays leads
to detection of most of the viral positive donations cost
effectively
• Individual Donation Nucleic Acid Testing (ID-NAT)
– Implemented in October 2005
– Primarily to reduce risk of HIV window period
transmission but also HBV transmission as well
Rationale for ID-NAT in South Africa
• HIV prevalence in blood donors 0.21%
• HBV prevalence in Blood Donors is 0.1%
• Implemented ID-NAT testing in October 2005
– ULTRIO® assay on the TIGRIS® platform for:
– HIV-1 RNA
– HCV RNA
– HBV DNA
– Serology testing for anti-HIV, anti-HCV and HBsAg
done concurrently
• Evaluated and implemented Ultrio Plus assay in May
2011 because of increased sensitivity for HBV
detection in window period
Geographic Distribution of Chronic HBV
Infection
HBsAg Prevalence
WHO
8% - High
2-7% - Intermediate
<2% - Low
HBV 5 Year data
%
New
%
Code
Active
Donations
2967492
Concordant (NAT
and HBsAg Pos)
232
0.008
3050
0.706
137
0.034
3419
0.090
ID-NAT only pos
217
0.0073
194
0.0449
65
0.0163
476
0.0125
HBsAg only pos
2
0.0001
124
0.0287
1
0.0003
127
0.0033
Grand Total
451
0.015
3368
0.780
203
0.051
4022
0.106
432064
Rejoined
%
Grand
Total
399863
%
3799509
Hepatitis B Summary
• 476 NAT+, HBsAg negative donations detected in 5 years
– Hundreds of cases of transmission via transfusion prevented
• ID NAT testing has had a significant positive impact on reducing
risk of HBV transmission via blood transfusion
• However still a risk of non detection of very low viral load
donations
• One confirmed HBV transmission on a donation that tested
negative with routine serology and ID-NAT
– Donor triggered look back as subsequent donation positive
• Ultrio Plus Assay evaluated and in 2010/11
Confirmed pre-ID-NAT WP transmission
case
• Donor triggered look back – RBC
• Platelet concentrate – Patient unable to be traced
• Donor details
–
–
–
–
–
47 year old white male (low risk, regular donor)
54 previous donations
Negative donation
– 26/11/2008
Date of Transfusion
– 10/12/2008
Positive donation
– 26/01/2009
ID-NAT WP transmission case
Donor
RBC recipient
26-Jan-09
9-Apr-09
30-Mar-09*
S/CO HBsAg 1st screen
352
0.27
743
S/CO HBsAg 2nd
screen
385
721
S/CO HBsAg 3rd
screen
395
760
S/CO Ultrio 1st screen
15.3
13.3
14.3
S/CO Ultrio 2nd screen
15.6
12.8
14.2
S/CO Ultrio 3rd screen
14.9
0.12
15.7
S/CO dHBV
23.1
invalid
25.2
anti-HBc IgM
Pos
Pos
anti-HBc total
Pos
Pos
anti-HBs
Neg
Neg
* 3.5 months after transfusion
Additional tests to Determine if Recipient
infection caused by Transfusion
• Donor plasma index donation (26/11/08)
– SANBS 3 out of 30 replicates positive
– Gen Probe 7 out of 30 replicates positive with Ultrio Plus
• Phylogenetic analysis/sequencing
– Donor and recipient – genotype A
– Intra group nucleotide divergence
• Donor/recipient 0.31% (99.7% Shared Identity)
• Transmission by Blood Tranfusion confirmed
Ultrio, Ultrio Plus, TaqScreen Study
performed
• Compare Sensitivity of NAT assays with a
range of samples
– 10 000 random samples
– 40 HIV ID-NAT yield samples
– 107 HBV ID NAT positive samples on Ultrio
– HBsAg positive, HBV NAT negative samples
– Other samples (HIV Window period transmission
sample and HBV window period transmission
sample)
Proportion reactive per NAT option on 107 Ultrio
HBV ID-NAT yield samples
% reactive
tested in 6 replicates in each test option
p< 0.00001
p< 0.00001
p< 0.00001
P= 0.00015
NAT option
Proportion HBV NAT reactive on WP*
and OBI yield samples
% reactive
NAT option
Percent ID-NAT reactive on HBsAg+/Ultrio- yield samples
% reactive (12 reps)
assay
Ultrio
Ultrio Plus
copies/ml*
*determined by probit analysis in Ultrio Plus against Eurohep standard
dona repli reac
ties cates tive
32
32
%
384 82 21,4%
384 241 62,8%
HBV ID-NAT Yields – One year Data Ultrio (2010 vs. Ultrio Plus 2011)
Ultrio
Ultrio Plus
increase
p value
775444
789948
pre-HBsAg WP
47 (1:16 499)
80 (1:9 874)
170%
0.005
post-HBsAg WP
10 (1:77 544)
17 (1:46 468)
167%
0.19
94 (1:8249)
162 (1:46 468)
172%
0.00004
HBV-NAT yield
151 (1:5204)
259 (1:3 050)
172%
<0.00001
HBsAg positive
820 (1:946)
841 (1:939)
103%
0.89
HBsAg+/DNA-
38 (1:20 406)
16 (1: 49 372)
971 (1:799)
1100 (1:718)
Donations
OBI
All HBV infections
0.002
111%
0.016
Viral load distribution in all HBV NAT yields
detected by Ultrio versus Ultrio Plus
Ultrio
P<0.01
P=0.15
Ultrio Plus
P=0.16
P<0.001
110
88
77
48
43
13
1-10
10-100
100-1000
HBV-DNA cps/mL
17
8
>1000
Estimated WP reduction with Ultrio and Ultrio
Plus (14.5 vs 24.7 days; 1.7 fold)
Start
WP
cps/ml
10000000
Ultrio
Plus
Ultrio
1000000
HBsAg
100000
10000
HBsAg S/CO=1
1000
3000 cps/ml
Ultrio 50% LOD 100
63 cps/ml
Ultrio Plus 50%
LOD 4.1 cps/ml
ID50 3.16 cps/
20 ml
screening
period
WP
transmission
risk
Ultrio
1:27 000
Ultrio PLus
1:43 000
10
1
0.1
0
0.01eclipse
10
20
12.9 days
WP
22.9 days
WP
30
24.7 days
days
Ultrio Plus
14.5 days
Ultrio
40
50
60
HBsAg
70
Probable OBI transmission case
Donor
Recipient
Drawing date
25/1/12
11/4/12¥
11/5/12
11/6/12
Status
RBC Issued
Look back
Follow up
Follow up
Ultrio Plus S/CO
Neg
15.3/15.5/15.1
15.6/14.9
Neg
Pos
22.7
neg
Neg
Neg
Pos
Neg
dHBV S/CO
4/7/12¥
31/1/13
HBsAg
Neg
Neg
Anti-HBc IgM
Neg
Neg
Pos
Pos
Anti-HBc total
Pos
Pos
Pos
Pos
Anti-HBs titre
<2
2.6
<10
284 IU/L
Viral load
1.6 cps/mL*
43 cps/mL
¥ 100 % homology of whole HBV genotype D genome sequence of donor sample 11/4/12 and
recipient sample 4/7/12 (analysis kindly performed by Dr Marco Koppelman, Sanquin,
Amsterdam)
* Estimated from 5/20 reps Ultrio Plus reactive by probit analysis ( 5.1% probability of
transmission estimated with ID50 of 316 virions)
Testing Strategy for Hepatitis B
• Countries with high incidence/prevalence of HBV
need to carefully review algorithms for HBV
testing and assay selection
– Maximise safety and minimise product discard
• High prevalence countries
– HBsAg and ID-NAT but not anti-HBc
• No discard of anti-HBc positive units (6-8% of products
usable)
• Majority of early and occult infections detected
• Minimal risk of not detecting post HBV DNA window period
donations and some OBI’s
• Ultrio Plus in ID-NAT format has significantly improved
sensitivity and reduced risk
Course of HBV markers and residual
transmission risk with ID-NAT
1st WP ~10 days
(Ultrio Plus)
2nd WP < 1day
(Ultrio Plus)
Vermeulen et al, Transfusion 2012;52:880-892.
OBI transmission risk
unknown
SANBS Algorithm for HBV Testing
•
•
•
•
ID-NAT and HBsAg testing
Concordant positive – confirmed
ID-NAT only (2 x U+ and dHxV)
Non repeat reactive – donation discarded, antiHBc and anti-HBs marker added
– 0.12% of donations discarded (mostly false positive)
– Donor not notified
– When donor returns
• Additional tests performed
• Blood can be used if all routine tests and anti-HBc negative
Algorithm for HBV Testing (cont’d)
• ID-NAT repeat reactive (2 out of 4), serology
negative
– Additional tests on plasma bag
– Donor recalled and additional tests done
– If confirmed positive defer donor
– If deferral, medical division contacts and counsels
donor
– If all tests on follow up donation negative (review
need for additional tests or re-instate)
HIV infections in six years of ID-NAT screening
of 4,520,230 donations
anti-HIV
HIV-RNA
7993 (96.5%)
HIV RNA +, anti-HIV +
concordant
HIV RNA +, anti-HIV–
window period
228 (2.8%)
82/228 (38.4%) HIV-Ag +
136 HIV-Ag-, RNA+ infections
avoided (1:33,237)
HIV RNA –, anti-HIV +
elite controller
64 (0.77%)
•
•
•
59 in first time donors (0.71%)
4 in lapsed donors (0.05%)
1 in repeat donor (0.01%)*
Impact of ID NAT on Blood Safety - HIV
• Significant positive impact on blood safety contributing to
major public health success story
– 136 ID- NAT positive, anti-HIV negative, p24 antigen negative
donations detected in 6 years of testing.
– Without ID-NAT there would have been numerous HIV
transmissions via blood transfusion
– Major public health success story
– Increased collections by 95 000 units over 5 years and increased
confidence in the blood supply
– Could increase Black donors from 7% to 31% of donor base over 5
years
• Since ID NAT implementation, no reported case of HIV
transmission since October 2005
– HIV prevalence in blood donors has increased (0.07% to 0.23%)
– Highlights impact of ID-NAT on improving blood safety
Summary
• Implementation of ID-NAT testing has resulted
in a significant increase in safety of the South
African blood supply compared to previous
testing strategy
• ID-NAT continues to interdict infectious
donations that are missed in mini pool format
• SANBS evaluation and one year data confirmed
that Ultrio Plus is more sensitive than Ultrio for
HBV
Thank You