Development of Immunity Following Financial Incentives for Hepatitis B Vaccination among People Who Inject Drugs
BACKGROUND:
People
who inject drugs (PWID) are at risk of hepatitis B virus (HBV) but have low
rates of vaccination completion. The provision of modest financial incentives
increases vaccination schedule completion, but their association with
serological protection has yet to be determined.
OBJECTIVE:
To
investigate factors associated with vaccine-induced immunity among a sample of
PWID randomly allocated to receive AUD$30 cash following receipt of doses two
and three ('incentive condition') or standard care ('control condition') using
an accelerated 3-dose (0,7,21 days) HBV vaccination schedule.
STUDY DESIGN:
A
randomised controlled trial among PWID attending two inner-city health services
and a field site in Sydney, Australia, assessing vaccine-induced immunity
measured by hepatitis B surface antibodies (HBsAb≥10mIU/ml) at 12 weeks. The
cost of the financial incentives and the provision of the vaccine program are
also reported.
RESULTS:
Just over
three-quarters of participants - 107/139 (77%) - completed the vaccination
schedule and 79/139 (57%) were HBsAb≥10mIU/ml at 12 weeks. Vaccine series
completion was the only variable significantly associated with vaccine-induced
immunity in univariate analysis (62% vs 41%, p<0.035) but was not
significant in multivariate analysis. There was no statistically discernible
association between group allocation and series completion (62% vs 53%). The
mean costs were AUD$150.5, (95% confidence interval [CI]: 142.7-158.3) and
AUD$76.9 (95% CI: 72.6-81.3) for the intervention and control groups
respectively.
CONCLUSION:
Despite
increasing HBV vaccination completion, provision of financial incentives was
not associated with enhanced serological protection. Further research into
factors which affect response rates and the optimal vaccination regimen and
incentive schemes for this population are needed.
By: Day CA1, Shanahan M2, Wand H3, Topp L4, Haber PS5, Rodgers C6, Deacon R7, Walsh N8, Kaldor J3, van Beek I6, Maher L3; Hepatitis Acceptability Group Vaccine Incentives Trial (HAVIT) Study Group.
- 1Discipline of Addiction Medicine, Central Clinical School (C39), Sydney Medical School, University of Sydney, NSW 2006, Australia. Electronic address: carolyn.day@sydney.edu.au.
- 2National Drug and Alcohol Research Centre, University of New South Wales, NSW 2052, Australia.
- 3The Kirby Institute, UNSW Australia, Sydney, NSW 2052, Australia.
- 4Cancer Council NSW, Woolloomooloo, NSW 2010, Australia.
- 5Discipline of Addiction Medicine, Central Clinical School (C39), Sydney Medical School, University of Sydney, NSW 2006, Australia; Drug Health Services, Royal Prince Alfred Hospital, Missenden Road, Camperdown,NSW 2050, Australia.
- 6Kirketon Road Centre, South Eastern Sydney Local Health District, Kings Cross, NSW 1340 Australia.
- 7Discipline of Addiction Medicine, Central Clinical School (C39), Sydney Medical School, University of Sydney, NSW 2006, Australia.
- 8Department of Epidemiology and Preventive Medicine, Monash University, 89 Commercial Road, Melbourne, Victoria 3004, Australia.
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