Hepatitis refers to inflammation of the liver. Hepatitis C is a type of viral hepatitis that happens due to an infection with the hepatitis C virus (HCV).
While some people will clear HCV completely, 55 to 85 percent develop a chronic infection, according to the World Health Organization (WHO). The Centers for Disease Control and Prevention (CDC) estimated that 2.4 million people in the United States had chronic hepatitis C in 2016.
Chronic hepatitis C can lead to serious consequences if it’s not treated. These include things like liver damage, cirrhosis, and liver cancer.
While we have vaccines for other causes of viral hepatitis, such as hepatitis A and B, there’s currently no vaccine for hepatitis C. Continue reading as we discuss why this is, how close we are to a vaccine, and more.
There’s currently no vaccine available for hepatitis C. There are a few reasons why developing a vaccine that protects against HCV remains challenging for researchers. Let’s explore some of these now.
HCVs are diverse
Hepatitis C viruses are quite diverse. There are currently eight genetically distinct groups, or genotypes, of HCV. Researchers identified the most recent genotype in 2018.
The genetic code of HCV genotypes differs by 30 percent, according to 2021 research. For comparison, the different hepatitis B genotypes only differ by 8 percent.
Ideally, a hepatitis C vaccine would protect against all or most genotypes of HCV. However, the high diversity of HCV makes achieving broad protection difficult.
HCV is an escape artist
HCV is also very good at getting away from the immune system. For example, proteins found on the outside of viruses are typically good targets for vaccines. In HCV, these proteins are called envelope proteins.
However, HCV has evolved ways to shield areas of its envelope proteins from the immune response. This means that it’s harder for neutralizing antibodies to reach these areas.
Additionally, a large number of subviral particles can be present in an HCV infection. These are particles that have the HCV envelope proteins but lack the genetic material needed to make more copies of the virus.
A 2021 review suggests subviral particles significantly outnumber actual HCV particles. Because of this, they can serve as an effective decoy for the immune system.
HCV presents research challenges
Although research has made great strides, studying HCV is still challenging. This can hamper vaccine development and testing.
We’re still trying to get more information on the immune response to HCV. Because some people clear HCV after an acute infection, researchers can study the immune response in these people to find factors important to clearing the virus and apply them to vaccine development.
Despite the knowledge we’ve gained from this research, only one vaccine has made it to phase 2 clinical trials. More on that later.
Learning more about immunity isn’t the only research challenge for HCV vaccine development. Some others include:
- a lack of good laboratory or animal models that can be used to study HCV infection
- a need for established markers that indicate protection from chronic hepatitis C, which can be used to determine vaccine effectiveness in clinical trials
- less research infrastructure where hepatitis C is prevalent, especially in marginalized populations
- a decrease in funding for HCV vaccine research, particularly during the COVID-19 pandemic
While we do have effective treatments for hepatitis C, it’s still important to develop a vaccine. This is because:
- Many people with chronic hepatitis C are not aware that they have it. This means that liver damage can continue to occur, and also that the virus can continue to be passed on to others.
- Liver damage from hepatitis C can remain even after the virus has been treated and cleared from the body.
- It’s possible to contract HCV again after treatment, particularly for those at a higher risk of hepatitis C.
- Resistance to some hepatitis C medications may develop, making them less effective.
- The medications used to treat hepatitis C are often expensive, which can limit access to them.
How will a hepatitis C vaccine work?
Overall, vaccines work by introducing your immune system to a microbe. In the case of viruses, this can be in the form of a whole virus or just a single component of a virus, such as a protein.
To date, many different hepatitis C vaccine candidates are in development. These use many different vaccine technologies to present HCV proteins to your immune system. Some examples include:
- Recombinant proteins. These consist of purified viral proteins.
- Virus-like particles. These particles contain the outside proteins of HCV, but don’t have any genetic material inside.
- DNA. This is genetic material that can provide instructions on how to make an HCV protein. The protein will then be displayed on the cell’s surface.
- Viral vectors. These contain genetic material inside of a harmless virus. The genetic material gives your cells instructions on how to make an HCV protein, which will be displayed on the cell’s surface.
With the ongoing success of the COVID-19 mRNA vaccines, it’s also possible that researchers will develop new vaccine candidates using this technology as well.
Clinical trials
So far, only a single hepatitis C vaccine candidate has made it into phase 2 clinical trials. While phase 1 clinical trials assess safety and dosage, phase 2 trials look at the safety and effectiveness of the vaccine in up to a few hundred people.
The results of this trial were published in 2021. Researchers tested a viral vector vaccine in 274 adults considered to be at risk for hepatitis C. Another 274 of these adults received a placebo injection.
The vaccine was found to lead to an HCV-specific immune response and didn’t cause any serious side effects. However, it also didn’t prevent chronic hepatitis C.
Other vaccine candidates for hepatitis C are being tested in phase 1 clinical trials. According to the National Institutes of Health, trials on another viral vector vaccine and a DNA-based vaccine are active.
Even though there’s no vaccine for hepatitis C, there are still steps that you can take to prevent the spread of HCV. These include:
- avoiding the sharing of injection drug equipment
- not sharing personal items that may have had contact with blood, such as razors, nail clippers, or toothbrushes
- using a condom or other barrier method during sex
- always receiving piercings or tattoos with tools that have been properly sterilized
- wearing gloves if you need to handle blood from someone with HCV
As researchers continue to work on a vaccine, treatments are available for both acute and chronic hepatitis C. The CDC estimates that over 90 percent of people can be cured of hepatitis C after treatment.
Treatment for hepatitis C typically lasts 8 to 12 weeks. Several different oral medications are approved by the Food and Drug Administration (FDA) to treat hepatitis C, including:
- elbasvir-grazoprevir (Zepatier)
- glecaprevir-pibrentasvir (Mavyret)
- ledipasvir-sofosbuvir (Harvoni)
- ribavirin (Copegus, Rebetol, Ribasphere)
- sofosbuvir (Sovaldi)
- sofosbuvir-velpatasvir (Epclusa)
- sofosbuvir-velpatasvir-voxilaprevir (Vosevi)
While undergoing treatment for hepatitis C, it’s also important to make lifestyle changes that promote liver health, such as:
- avoiding alcohol
- checking in with your doctor before taking medications, supplements, or herbal remedies, as some can also damage the liver
- getting vaccinated for hepatitis A and hepatitis B
Treatments for hepatitis C can be expensive. If you’re concerned about cost, there are resources available to help. Get more details here.
The table below shows some of the notable differences between hepatitis A, B, and C.
There’s currently no vaccine for hepatitis C. There are several reasons for this, including the genetic diversity of HCV, the virus’s ability to evade the immune system, and various research challenges related to HCV.
Although researchers are still working on developing a hepatitis C vaccine, there are medications that can clear HCV in most people. However, these are expensive, and it’s also still possible to contract HCV again after treatment.
You can take steps now to help prevent contracting HCV. These include not sharing personal items, not sharing injection drug equipment, and wearing gloves when handling blood that may contain the virus.