Why is there no vaccine for the hepatitis C virus?
The need for a hepatitis C vaccine is indisputable. But if that’s the case, why is there no vaccine alternatives? Why is it that there’s no hepatitis C vaccine as of now?
We have two main reasons. One has to do with the diversity of the hepatitis C virus, and the other relates to the host’s immunity.
- Hepatitis C diversity: According to studies on the hepatitis C virus, this is not a new disease. It has around 1000 years in circulation. The condition evolved in particular regions of the globe and gave rise to 6 types and more than 100 subtypes. Each of them shares 80% of the genes, and some of them caused an epidemic among drug users in past years, especially subtype 1a, 1b, and subtypes 3a, 2a, and 4a. These types and subtypes only replicate in hepatocytes and have a high rate of mutations (one nucleotide for every cycle of replication). Thus, there is an impressively high number of variabilities in terms of genetics, which makes it harder to create an accurate and genuinely reliable vaccine.
- Host immunity problems: Some patients have a capable immune system that clears the disease in the acute phase. Others do not have the same luck, and the exact mechanisms behind this difference are not clearly understood. Moreover, the evidence shows that chimpanzees who recovered from hepatitis C can be reinfected sometimes. They do have some protection after being immunized, but it is not complete, not even with the same viral subtype. Thus, it appears that a vaccine will prevent the progression and the aggressiveness of the disease instead of providing complete immunity against hepatitis C.
