Why Is There No Vaccine For Hepatitis C?

Obstacles and Possibilities with Hepatitis C Immunization

doctor prepping a vaccine
What don't we yet have a vaccine for hepatitis C?. Joe Raedle / Staff / Getty Images

The of Importance of a Hepatitis C Vaccine

The hepatitis C virus (HCV) infects at least 170 million people worldwide and about four million people in the United States. It is a big public health problem because most acute hepatitis C infections become chronic which can lead to further liver problems like cirrhosis and cancer. A hepatitis C vaccine would be a great victory for preventative medicine and public health, and despite the technical problems involved, scientists are working and making good progress toward developing an effective and affordable vaccine.

According to the CDC, for every 100 people infected with the virus, 70 to 85 will go on to develop a chronic infection. Among those who develop a chronic infection, 60 to 70 will develop liver disease, five to 20 will develop cirrhosis (over a period of 20 to 30 years) and one to five will die from either cirrhosis or liver cancer.

Where are We at in Finding a Vaccine for Hepatitis C?

One vaccine currently being tested in a trial which was set to end in 2016 has shown promise. The vaccine in development deploys the body's own immune system to ward off infection with HCV using a two-tier approach that first triggers and then enhances the immune response. Depending on whether initial testing shows the vaccine is effective in preventing chronic hepatitis C with a reasonable safety profile, it may graduate to testing in a larger trial. Therefore, public access to the vaccine is likely still years away.

What Are the Obstacles to Creating a Hepatitis C Vaccine?

Currently, there is no hepatitis C vaccine for three basic reasons:

  1. HCV has different genotypes. There are currently seven genotypes of hepatitis C which are basically genetic variations of a theme. They're hepatitis C viruses, but they have enough genetic difference to be classified in distinct genotypes. Since hepatitis C has at least seven genotypes, several different vaccines would be needed in order to offer protection each genotype.

    It might be helpful to compare genotypes with members of a family. A family is made up of many different people, each with their own personality and looks, but all are still members of a family. It's very similar with the hepatitis virus. There are different genotypes, but they are all hepatitis C viruses.

  1. HCV mutates very easily. This means that some of its genetic code can change a little bit when it replicates itself. The result is a virus that keeps its genotype, but is different enough to confuse a vaccine. In other words, if a vaccine were made against a hepatitis virus present today, it would not work against the offspring of the virus (because they are too different genetically) by the time the vaccine was released.
  2. There is no effective small animal model or cell culture system. This makes vaccine development very challenging because researchers can't see how the virus really works in a natural environment. Really, scientists don't truly understand the whole life-cycle of the hepatitis C virus because infecting liver cells (called hepatocytes) in a dish outside of the body is very difficult.

    This may be changing. Researchers from the University of California, San Diego School of Medicine announced in July 2008 that they have developed a culture system that can model infection with the hepatitis C virus. This is great news for HCV vaccine development.

​Preventing Hepatitis C Transmission

Until a vaccine is available to prevent the transmission of hepatitis C, the following precautions can be taken to dramatically reduce your risk:

  • Using condoms
  • Avoiding sharing needles, toothbrushes and razors
  • Demanding a sterile environment and safe practice during health procedures, or when getting tattoos and piercings

What Else Can You Do?

In addition to avoiding risk factors for hepatitis C, there are other things you can do to lower your risk of the complications of hepatitis C including cirrhosis and liver cancer.

  • Those who were born between 1945 and 1965 should be tested for hepatitis C, as many people who carry the virus not have any obvious risk factors.

Sources:

Abdelwahab, K., and Z. Said. Status of Hepatitis C Virus Vaccination: Recent Update. World Journal of Gastroenterology. 201. 22(2):862-873.

Centers for Disease Control and Prevention. Viral Hepatitis – Hepatitis C Information. Updated 10/17/16. https://www.cdc.gov/hepatitis/hcv/cfaq.htm#cFAQ39

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