Investigators from the USA and China assessed whether hepatitis C virus (HCV) infection and vaccination can protect against viral persistence in humans.
The researchers conducted a study of injecting drug users.
They identified 164 people who had no evidence of previous HCV infection and 98 individuals who had been previously, but were not currently, infected with HCV.
The incidence and persistence of HCV viremia in these groups was compared over four consecutive 6-month periods.
Of participants without previous infection, the incidence of HCV infection was 21%.
| Those previously infected half as likely to develop new HCV viremia.
By contrast, people previously infected were half as likely to develop new viremia (12%), even after accounting for risk behavior (hazard ratio, 0·45).
Furthermore, in HIV-1-negative people, those previously infected were 12-times less likely to develop persistent infection than people infected for the first time (odds ratio 0·05). The median peak HCV RNA concentration was found to be 2 logs lower.
HCV persisted in 6 of 6 HIV-1-positive people, even in one man who had previously cleared HCV infection when he was HIV-1 negative.
Shruti H. Mehta, of the Johns Hopkins School of Public Health, Baltimore, Maryland, USA, said on behalf of fellow colleagues, "There is an alarming frequency of HCV infection and persistence among injecting drug users."
"Our data suggest that immunity against viral persistence can be acquired, and that vaccines should be tested to reduce the burden of HCV-related liver disease," it was concluded.