One step closer to a Hepatitis C vaccine

Hepatitis C affects about 68,000 people in British Columbia, but there is currently no vaccine for the virus.

New research has confirmed that infection with one hepatitis C virus (HCV) type does not protect against subsequent infection with different types of the virus, and that a prophylactic vaccine consisting of a cocktail of virus types might be the way forward.

Lead author and school of population and public health postdoctoral fellow Nazrul Islam discusses the findings, including how a vaccine could save people’s health, and the health system’s money.

Why is it important to develop a HCV vaccine?

SPPH postdoctoral fellow Nazrul Islam

The consequences of hepatitis C to people’s health can include liver cancer and death. As well, while newer hepatitis C treatments (direct-acting antivirals) are highly effective, with cure rates of around 95%, and have fewer side-effects, they are very expensive, costing from $45,000 to up to $110,000 for a 12 to 24 week course in British Columbia.

Since people are at risk of a second (or third) infection, even after a successful treatment, reinfections add a significant monetary toll on the health system. Thus, an effective hepatitis C vaccine is needed to prevent (re)infections, which will ultimately help the health system as well as patients.

What’s the hold up in developing a HCV vaccine?

The major challenges in developing an effective vaccine include that there are multiple types of viruses causing HCV, a lack of suitable animal models other than chimpanzees, and a lack of data on the complexities as to how our body’s immune system responds to HCV.

Very small studies on chimpanzees reported contradictory results, and data on human studies was scarce because it requires examination of a patient’s full history, from infection, to clearance, to reinfection, to the consequences of this. This is very difficult to gather because it is unethical to have people exposed to the same or different type of virus and it requires a long period of follow-up.

How has your research brought us one step closer to a hepatitis C vaccine?

Previous studies have indicated that reinfection with HCV results in a higher likelihood of clearing the virus and a shortened period of infection. In our study, we followed 452 individuals who cleared their first infections, and became reinfected with the same or a different virus type, and observed whether they were able to clear the second infection. This is the first study to examine this after controlling for other factors that might affect the outcome after reinfection, and in a large human population. Even people with stronger immune systems, i.e., individuals who were able to clear their first infections without any treatment, were almost half as likely to clear their second infection if the second infection was caused by a different virus type than the first. This indicates that protection against a particular HCV virus type is not able to protect against a different HCV virus type.

While a vaccine that prevents infection is the ultimate goal, it is not yet a reality. Based on our results, and given the genetic diversity of HCV virus types, it is probably more pragmatic to develop a prophylactic vaccine containing a mix of HCV types that aids clearance of the virus, creating partial protective immunity. This would shorten viral presence in the body, and prevent long-term consequences of viral persistence including liver cirrhosis and liver cancer.

Not only will it improve peoples’ quality of life by preventing chronic HCV infections and/or reducing disease duration, it will save a significant amount of public expenditure by reducing HCV treatment cost, and healthcare costs of treating liver-related complications.

The paper was published in Scientific Reports.

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