Hepatitis B risk factors: how it spreads and who is at risk

What hepatitis B is

Hepatitis B is a viral infection that causes inflammation and damage in the liver (NIDDK). It can be acute, a short-term infection that goes away, or chronic, a long-lasting infection (NIDDK). People with an acute infection usually get better on their own, and some people with chronic hepatitis B need treatment (MedlinePlus).

Thanks to the vaccine, hepatitis B is not very common in the United States (MedlinePlus). Researchers estimate that less than 0.35% of people in the US, about 1.17 million, have chronic hepatitis B, and most of them were born outside the United States (NIDDK).

How the virus spreads

The virus spreads through contact with an infected person's blood, semen or other body fluids (NIDDK). NIDDK lists these ways (NIDDK):

• being born to a mother who has hepatitis B
• unprotected sex with an infected person
• sharing needles or other equipment used to inject drugs
• an accidental stick with a needle used on an infected person
• tattoos or piercings done with tools that were not sterile
• contact with an infected person's blood or open sores
• using an infected person's razor, toothbrush or nail clippers

In the United States, adults get hepatitis B mainly through infected blood entering through the skin, most often during injection drug use, or through sexual contact (NIDDK).

You cannot get hepatitis B from coughs or sneezes, hugging, shaking or holding hands, sitting next to someone, or sharing food, drinks or eating utensils (NIDDK).

Who is more likely to get hepatitis B

Anyone can get hepatitis B, but the risk is higher in some groups (MedlinePlus). Combining the NIDDK and MedlinePlus lists (NIDDK) (MedlinePlus):

• Babies born to a mother with hepatitis B. The virus can pass from mother to child during birth.
• People born where hepatitis B is common, and people born in the US who were not vaccinated as babies and whose parents come from an area where many people have hepatitis B. MedlinePlus also lists people who have lived in or often traveled to those parts of the world.
• People who live with, or have sex with, someone who has hepatitis B, and people with several sex partners or a past sexually transmitted disease.
• Men who have sex with men.
• People who inject drugs or share needles, syringes or other drug equipment.
• Health care and public safety workers and others whose jobs expose them to blood, needles or body fluids.
• People with HIV or hepatitis C (see hepatitis C risk factors), and, on the MedlinePlus list, people with diabetes.
• People on kidney dialysis.
• People who live or work in a jail or prison.

Hepatitis B is more common in some parts of Africa, Asia, the Middle East, Eastern Europe and South America, where 2% or more of people have chronic infection, and in some areas of sub-Saharan Africa and Asia more than 8% do (NIDDK).

Why age at infection matters

Most healthy adults, and children older than 5, who get hepatitis B recover and do not develop a chronic infection (NIDDK). The younger a person is when infected, the more likely the infection is to become chronic. NIDDK gives these figures for how often chronic infection develops (NIDDK):

• about 90% of infants younger than 1 year
• 25% to 50% of children aged 1 to 5
• about 5% of adults

People with a weak immune system, such as people with HIV, may also be more likely to develop chronic hepatitis B (NIDDK).

Why chronic hepatitis B matters

Many people with hepatitis B have no symptoms, and people with chronic hepatitis B may have few symptoms until complications appear, sometimes decades after infection (NIDDK) (MedlinePlus). Chronic hepatitis B can lead to cirrhosis, liver failure and liver cancer (NIDDK). See cirrhosis risk factors and liver cancer risk factors.

In people who have or have had hepatitis B, the virus can become active again later in life (MedlinePlus). NIDDK says the risk of this reactivation applies to people taking medicines that weaken the immune system (such as cancer chemotherapy, some medicines for immune conditions or after a transplant, and corticosteroids taken for more than a few weeks), people taking medicines for hepatitis C, and people with HIV who stop certain HIV medicines (NIDDK).

Because so many people have no symptoms, screening matters. The hepatitis B screening check shows who is advised to get tested and how often.

How to lower your risk

The best way to prevent hepatitis B is the hepatitis B vaccine (MedlinePlus). It is most often given as three shots over 6 months, and some adults can get it in two (NIDDK). NIDDK says doctors recommend it for everyone age 59 and younger who has not been vaccinated, and for older adults who are more likely to be infected, have chronic liver disease or want the vaccine (NIDDK).

You can also lower your chance of infection by (NIDDK) (MedlinePlus):

• not sharing needles or other drug equipment
• wearing gloves if you have to touch another person's blood or open sores
• making sure a tattoo artist or piercer uses sterile tools
• not sharing toothbrushes, razors or nail clippers
• using a latex or polyurethane condom during sex

If you think you have been in contact with the virus, see a doctor right away. A dose of the vaccine, and in some cases hepatitis B immune globulin (HBIG), given soon after contact, preferably within 24 hours, can help prevent infection (NIDDK).

Common questions

Can hepatitis B pass from a mother to her baby?

Yes, it can spread during birth (NIDDK). A baby born to a mother with hepatitis B should get the hepatitis B vaccine and HBIG right after birth, which greatly lowers the chance of infection, and NIDDK says mothers with hepatitis B can safely breastfeed when these steps are taken (NIDDK).

Which risk factors can I change?

Where you were born and how you were infected as a child cannot be changed. Getting vaccinated, not sharing needles or personal items like razors, and using condoms are steps on the NIDDK and MedlinePlus lists (NIDDK) (MedlinePlus). If you take a medicine that weakens the immune system, ask your clinician about hepatitis B testing, and do not stop a medicine without talking to your clinician.

Is there a cure?

Not everyone with chronic hepatitis B needs treatment. If blood tests show the virus could be damaging the liver, antiviral medicines can lower the chance of liver damage and other problems (NIDDK). Researchers are studying new drugs to cure hepatitis B (NIDDK).