How hepatitis C transmission happens

Key points

Hepatitis C is transmitted when the blood of a person with hepatitis C comes in contact with the blood of another person.
Many factors influence the chance that a person will get hepatitis C: the type of activity that exposes them to the virus, the prevalence of hepatitis C in their population, and social and structural factors that influence whether the person knows about and can access prevention services.
In Canada, the primary population affected by hepatitis C has shifted over time from individuals who received unscreened blood products to people who share drug use equipment, particularly injection drug use equipment.
Immigrants and newcomers may have been exposed to hepatitis C through different routes in their countries of origin.

Hepatitis C is transmitted when the blood of a person with hepatitis C comes in contact with the blood of another person. Hepatitis C is highly transmissible because only trace amounts of blood (even amounts not visible to the eye) are required to pass on hepatitis C. The hepatitis C virus can live outside the body for several days or, in some cases (e.g., inside certain types of syringes), for weeks.

Because hepatitis C is mainly transmitted through blood-to-blood contact, any activity involving such contact poses a high risk of transmission. That said, the actual chance of transmission depends not only on the type of activity that exposes a person to the virus, but also on how common hepatitis C is in the population, and on social and structural factors that influence whether the person knows about and can access prevention services. There are various transmission routes, which each have different levels of risk associated with them.

These include:

Sharing injection drug use equipment: The most significant hepatitis C transmission route in Canada is the sharing of equipment used to inject drugs (e.g., needles, syringes, cookers, filters). Sharing needles and other injection drug use equipment can lead to direct blood-to-blood contact, resulting in a high risk of hepatitis C transmission.
Sharing equipment for smoking or snorting drugs: Sharing equipment used for smoking or snorting drugs (e.g., pipes or straws) can transmit hepatitis C. This is because blood-to-blood contact can occur when someone uses equipment previously used by a person with cracked, bleeding lips or a tiny nosebleed.
Unsterilized tattoo or piercing equipment: Tattooing and piercing can transmit hepatitis C because of the potential for blood-to-blood contact, but the risk depends on the context. When sterile or new equipment is used (like in a professional tattoo or piercing studio), there is no risk for hepatitis C transmission. There is an increased risk for hepatitis C transmission in unregulated settings (e.g., prisons) where tattoo and piercing equipment is shared because there is limited or no access to sterile and single-use equipment, as well as in countries where infection control practices for tattooing and piercing are not regulated.
Transmission during sex: Although sexual transmission of hepatitis C is considered uncommon, it can occur, particularly when certain biological and behavioural factors increase the likelihood of blood-to-blood contact. Research shows that gay, bisexual and other men who have sex with men (gbMSM) are at higher risk, especially those living with HIV or other sexually transmitted and blood-borne infections like syphilis, which can cause mucosal damage and make transmission more likely. Hepatitis C has also been detected more often in the semen of gbMSM co-infected with HIV. Behavioural factors like condomless anal sex, rough or prolonged sex, fisting, group sex, and drug use before or during sex, particularly among some gbMSM, may further increase transmission risk. In some cases, it’s difficult to separate the role of sexual activity from the sharing of drug use equipment during sex. Among heterosexual monogamous couples, sexual transmission is rare. However, heterosexual people with multiple partners face higher risks, which may be due to behavioural factors like engaging in higher risk sex or increased exposure to sexually transmitted and blood-borne infections. While there is limited research on sexual transmission of hepatitis C among transgender individuals, behavioural and biological factors probably influence the risk for potential virus transmission in this population.
Perinatal transmission: Hepatitis C can be passed from parent to child during pregnancy or childbirth. Although this is not a common transmission route in Canada, it may be in other countries. If a pregnant person has a hepatitis C infection, there's up to an 8% risk hepatitis C could be passed to their infant. There is no evidence to suggest that hepatitis C can be passed from parent to child while breastfeeding/chestfeeding.
Unsafe medical procedures or traditional healing practices: Medical and dental procedures, blood transfusions and traditional healing practices (e.g., acupuncture and wet cupping) can potentially transmit hepatitis C when there is blood-to-blood contact, but the level of risk depends on the context.
- Canadian context: Strict infection control practices in Canada make the risk associated with medical procedures and traditional healing practices low to nonexistent. The implementation of routine blood screening in 1992 eliminated the risk of hepatitis C transmission from blood transfusions in Canada. People who received transfusions before 1992 may still be at risk for hepatitis C.
- Outside of Canada: Although the risk of hepatitis C transmission from medical procedures is low to non-existent in Canada, the risk can be higher in other countries where infection control practices are more limited. Immigrants and newcomers to Canada may have been exposed to the virus through such procedures. People who travel to these regions may also be exposed if they receive medical, dental or traditional care while abroad.
Sharing personal care items: Sharing razors, toothbrushes, nail clippers and other household items that can cause small cuts or retain traces of blood can pass hepatitis C, but this is not a common transmission route.

Activities that cannot pass hepatitis C

Hepatitis C cannot be passed through casual contact (e.g., sharing toilets, drinking glasses or eating utensils) or hugging, kissing or touching a person with hepatitis C, as there is no potential for blood-to-blood contact.

See Prevention & Harm Reduction for more information on how to reduce the chances of hepatitis C transmission.

Different levels of risk for hepatitis C

While individual behaviours play a role in hepatitis C transmission, a person’s risk is shaped by more than just their actions. Broader social and structural factors, like financial insecurity, housing instability and the criminalization of drug use, also shape a person’s hepatitis C transmission risk.

For example, people who use drugs and who lack stable housing may have no choice but to use in public spaces, where rushed or unsafe conditions can limit their ability to practise safer drug use (e.g., avoiding sharing drug use equipment), thereby increasing their risk for hepatitis C transmission. As a result, some communities, such as people who use drugs, are disproportionately impacted by hepatitis C.

Being a member of these communities is not a risk factor for hepatitis C; rather, it is the unequal distribution of resources, power and opportunities — driven by factors like stigma, discrimination and colonialism — that creates health inequities for these communities. These inequities make it harder for people to avoid exposure to hepatitis C and to access the prevention and healthcare services they need. Recognizing how risk is created and reinforced by these social and structural factors can provide insights into why some individuals may be at higher risk for hepatitis C than others.