Hepatitis B is a liver infection that inflames the organ and impacts its ability to function. It can be either acute (short-term) or chronic (long-term), and is estimated to impact between 880,000 and 1.89 million people in the United States.
Those who leave chronic hepatitis B untreated have a 25% to 40% risk of developing liver cancer at some point in their lives, according to the Hepatitis B Foundation.
The good news: There's a vaccine for hepatitis B that, according to the Centers for Disease Control and Prevention (CDC), can help to prevent millions of deaths worldwide. The bad news: Only about 1/3 of American adults are currently vaccinated.
"Vaccines are safe, effective and save lives," says Dr. Jennifer Brull, president of the American Academy of Family Physicians (AAFP). "They are one of our best tools to prevent severe illness, hospitalizations and death in our communities. ... Being vaccinated against diseases helps build a community of immunity and protects those more vulnerable to disease who may not be able to get vaccinated."
Here's what health experts want you to know about hepatitis B and how vaccinations can help prevent its spread.
Hepatitis B is a contagious liver infection that's transmitted through blood, semen or another type of bodily fluid from a person who's infected with the virus, according to the CDC.
The severity can range from a "mild, short-term, acute illness lasting a few weeks to a serious, long-term, chronic infection," the CDC adds. Those at higher risk include healthcare workers, drug users, travelers in areas where the infection is widespread and people who have multiple sex partners.
"The best way to prevent hepatitis B is to always have protected sex - use a condom - and, if you use intravenous IV drugs, avoid sharing needles," Brull says.
Plus: "Preventing perinatal hepatitis B is important because most people with hepatitis B got infected as infants or young children when their immune systems were not fully developed," according to the CDC.
Yes, there is a vaccine for hepatitis B; it's usually administered in a series of two to three shots over the course of six months, which provides long-term protection.
The CDC recognizes the hepatitis B vaccine as the best way to prevent getting infected and recommends it to essentially any age group that hasn't been vaccinated yet: infants, children and adolescents under 19, adults 19 to 59 and adults 60 and older with risk factors for hepatitis B. It's also safe to receive while pregnant.
Vaccines as a whole work by imitating an infection to teach the body how to recognize and defend itself from disease without experiencing the dangers of an actual infection, according to the CDC.
"They do so by exposing the body to an active ingredient called an antigen which triggers an immune response," Brull says. Depending on the vaccine, "this immune response can protect you for many years or your entire life."