Theme: Epidemiology & Public Health Research Year: 2022
Background:
With the introduction of direct-acting antivirals (DAAs), an initial rise in hepatitis C virus (HCV)
reinfection rates was observed in some settings. In parts of Scotland, major reductions in the
population-level prevalence of HCV infection among people who inject drugs (PWID) – associated
with rapid scale-up of DAAs – have also now been observed. To gauge the impact of these changes,
we examined reinfection rates over time and by region, comparing areas with greater and lower
intensity of treatment.
Methods:
Using nationally linked HCV clinical and laboratory test data, a retrospective cohort of PWID who
commenced treatment during 2015-2020 and achieved a sustained viral response (SVR) were
followed up for reinfection – defined as a positive HCV antigen or RNA test – to December 2021.
Results:
Of 5093 SVRs among 4961 PWID, 3615 (71%) had an HCV RNA or antigen test post-SVR. Of those
retested, we identified 350 reinfections (6.2/100 person-years (PY)). The reinfection rate increased
from 4.6/100PY in 2016-17 to 6.2/100PY in 2018-19 and 7.6/100PY in 2020-21. Considering the
region with the largest scale-up of DAAs and greatest reduction in the population prevalence of HCV
within Scotland, reinfection rates increased initially from 8.6/100PY in 2016-17 to 13.8/100PY in
2018-19 but has fallen to 6.2/100PY in 2020-21. Of the cumulative cohort treated since 2015 (and
not known to have died or migrated), a declining proportion had been re-tested for HCV RNA postSVR with each year, from 47-62% pre-pandemic to 23-35% during the pandemic.
Conclusion:
Our data suggest that rising HCV reinfection rates among PWID in Scotland may have peaked in
areas with the greatest scale-up of DAAs and marked reductions in population prevalence of HCV.
However, additional effort is needed to increase HCV testing among PWID, including those treated
before the pandemic, to fully assess this and ensure reinfections are diagnosed and retreated.
Disclosure of Interest Statement:
This study is funded by the National Institute for Health Research (NIHR) Programme Grants for
Applied Research programme (Grant Reference Number RP-PG-0616-20008). The views expressed
are those of the author(s) and not necessarily those of the NIHR or the Department of Health and
Social Care. SJH received honoraria from Gilead, unrelated to the submitted work.