Around one in seven gay and bisexual men cured of hepatitis
C at major treatment centres in Germany has become reinfected since 2014,
according to findings from the German Hepatitis C Cohort presented on Friday at
the 16th European AIDS Conference in Milan.

At least half of these men became reinfected within a year
of completing treatment and all reinfections occurred within 18 months.

The risk of reinfection is thought to be highest among men
who share drug injecting equipment during sex – chemsex – but Dr Stefan Mauss of
the Center for HIV and Hepatogastroenterology in Dusseldorf said that sharing
drug injecting equipment during sex might explain only a quarter of these cases
of reinfection.

People infected with hepatitis C who are cured of the
infection are vulnerable to reinfection. Although a proportion of people will
cure hepatitis C infection spontaneously, it is not clear if a successful
response to previous treatment increases the likelihood of clearing HCV.

Several studies with varying periods of follow-up have
looked at the risk of reinfection among men who have sex with men in Europe.

A study
in London
carried out prior to the introduction of direct-acting antiviral
treatment found an incidence of reinfection of 9.6 cases per 100 person years
of follow-up.

More recently, a
multicentre study in western and central Europe
treatment found an
incidence of reinfection of 7.3 per 100 person years. The study also found big
variations between cities. 

The German Hepatitis C Cohort collects information on
everyone treated with direct-acting antivirals at nine treatment centres in
Germany. In this analysis, investigators reviewed reinfection rates among 1533
people who had been cured of hepatitis C and compared rates of reinfection
according to potential risk factors.

Thirty-two cases of reinfection were identified, all in men.
Five cases occurred in men who injected drugs (an incidence of 0.96%).
Twenty-seven cases occurred in men who have sex with men (an incidence of
13.1%). Only seven of the men who have sex with men said that they had used
intravenous drugs, suggesting either a discomfort about disclosing drug use or
predominantly sexual transmission.

Reinfection occurred fairly soon after completing treatment,
in a median of 53 weeks (range 36-70 weeks).

In almost half of cases (44%) the reinfection was a new
genotype.

A study of acute HCV infections at one of London’s largest
sexual health and HIV clinics, the Mortimer Market clinic, found that among 95
people diagnosed with acute HCV infection between 2015 and 2017, 27% reported
condomless anal intercourse as their only risk factor. Almost all those acutely
infected with HCV were men who have sex with men (94%) and only 27% reported
injecting drugs.

Almost a quarter of the infections (22 cases) occurred in
people who were HIV negative, leading presenter Emily Chung to recommend that
risk-based screening for HCV infection should now be considered for
HIV-negative men who have sex with men.