All adults 18 and older should be screened at least once in their lifetime for hepatitis B, according to the latest advice from the CDC. The updated recommendation, published in the agency’s Morbidity and Mortality Weekly Report on March 10, calls for using a blood test that looks at three specific markers related to the hepatitis B virus (HBV), not a single test as previously recommended.

Chronic HBV infection, which affects an estimated 580,000 to 2.4 million people in the U.S., causes inflammation of the liver and increases the risk of cirrhosis and liver cancer—but two-thirds of infected individuals might not be aware of their condition, the CDC says.

HBV is transmitted through blood, semen, and other bodily fluids, such as may occur with unprotected sex and injection drug use, and from mother to fetus during delivery. Safe and effective vaccines are available for prevention, and if you contract the virus, there is no cure, but there are good antiviral treatments that, along with monitoring, can reduce illness and deaths.

Previously, the CDC advised screening only for people known to be at increased risk for hepatitis B, but such “risk-based testing alone has not identified most persons living with chronic HBV infection,” the new report says. Hence the appeal for universal screening now. The new recommendation—the first since 2008—should help the World Health Organization meet its goal for the U.S. to increase the percentage of people who are aware that they have hepatitis B, from 32 percent currently to 90 percent by 2030.

Also in the update is the addition of three groups of people considered at increased risk for HBV who should be screened periodically (not just once): those who have a history of multiple sex partners or sexually transmitted infections, those with a current or past hepatitis C infection, and anyone who is or has been incarcerated. All pregnant women should also be screened, regardless of their history of past testing or vaccination. A summary of the new recommendations, including the full list of people at increased risk for HBV, can be found here.

HBV is just one of several viruses that can infect the liver. In an updated recommendation issued in March 2020, the U.S. Preventive Services Task Force (USPSTF) similarly advised one-time screening for the hepatitis C virus in all adults ages 18 to 79 even if they have no symptoms of liver disease, with periodic follow-up screening in high-risk people. The USPSTF is an independent panel of experts that develops recommendations for clinical preventive services based on current evidence.