A cheat sheet from Andrew Reynolds on the most common infectious disease in the world

Hepatitis B (HBV) is a virus that infects the liver, and is the most common infectious disease in the world. In the United States, an estimated 850,000 to 2.2 million people live with HBV; about 10% of people living with HIV in the U.S. also have HBV. In recent years there have been increases in HBV cases among people who inject drugs (PWID) and in mother-to-child (known as vertical) transmission in the U.S., directly related to the opioid crisis. Screening, vaccination, and prevention and HBV treatment are essential tools for addressing this public health issue. 

Hepatitis B transmission

Hepatitis B is transmitted in much the same way as HIV. It’s spread when blood, semen, vaginal fluids, and other bodily fluids get into a person who does not have the virus or is not protected by immunity (through vaccination or cleared infection). It is also commonly transmitted during birth. The following have been associated with risk of transmission:

  • vertical (perinatal) transmission
  • condomless sex with an infected partner
  • sharing syringes and other drug-injection equipment (cookers, cotton, water, etc.)
  • sharing household items such as razors or toothbrushes with an infected person
  • other blood-to-blood contact
  • occupational exposure from needlesticks or other risks of blood-to-blood contact.

Testing for hepatitis B

Most people who acquire HBV don’t know it because there are rarely signs or symptoms in the acute or chronic stages of infection. Over time, as the liver is damaged, noticeable symptoms may arise, but screening (testing) for the virus is the only way to determine if you have HBV.

Who should get tested:

People from endemic regions of the world:

  • persons born in a country with HBV rates greater than 2%
  • U.S.-born individuals who did not receive a vaccination, and whose parents were born in a country with HBV rates greater than 8%

People with certain medical conditions:

  • individuals who are pregnant 
  • babies born to persons who have acquired HBV 
  • individuals on hemodialysis 
  • people needing immunosuppressive therapy (such as chemotherapy or those receiving organ transplants)
  • people with chronic HCV infection before undergoing DAA therapy
  • donors of blood, plasma, organs, tissues, or semen
  • anyone with an unexplained elevated ALT/AST 


  • people who inject drugs
  • men who have sex with men
  • people living with HIV 
  • household, needle-sharing (including injection equipment), or sex partners of people with chronic HBV 
  • people who are the sources of blood or body fluids resulting in a potential HBV exposure (such as an occupational needle stick or blood splash or sexual assault) where post-exposure prophylaxis may be necessary


Vaccination for hepatitis B

Hepatitis B is vaccine preventable. Vaccination against HBV is safe and highly effective; it is successful over 95% of the time. After the first dose, the vaccine is administered one month and six months later. Adults may be eligible for a two-dose sequence, in which the first dose is administered and the second dose is given at least one month (minimum of 28 days) later. The vaccine remains effective the rest of your life with no need for a booster shot ever. 

Who should be vaccinated against HBV:

On April 1 this year, the CDC’s Advisory Committee on Immunization Practices issued updated and simplified hepatitis B vaccination recommendations:

“HepB vaccination is recommended for adults aged 19 to 59 years and adults > 60 years with risk factors for hepatitis B. Adults aged >60 years without known risk factors for hepatitis B may also receive HepB vaccines. Infants and all other persons aged <19 years are already recommended to receive HepB vaccines.”

In other words: Everyone from the age of 19 to 59 should get vaccinated! Universal vaccination is a simple way to make sure that no one falls through the cracks, and takes away the stigma of having to ask people for specific risk factors for HBV. Everyone younger than 19 has already had universal screening recs, so routine vaccines should be happening. If not, get vaccinated whenever you can make it happen…again, with no questions asked.

For anyone over the age of 60, the following risk factors should be considered for hep B vaccination:

Persons at risk for sexual transmission of HBV, including:

  • susceptible sex partners of hepatitis B surface antigen (HBsAg)-positive persons
  • sexually active persons who are not in a long-term, mutually monogamous relationship (e.g., more than one sex partner during the previous 6 months)
  • anyone seeking care for a sexually transmitted disease
  • men who have sex with men

People who are at risk of blood-borne exposures, including:

  • People who inject drugs
  • susceptible household contacts of HBsAg-positive persons
  • health care and public safety workers at risk for blood exposure
  • anyone with end-stage renal disease
  • residents and staff of facilities for developmentally disabled persons

Other people: 

  • Travelers to regions with intermediate or high rates of endemic HBV infection
  • People living with hepatitis C
  • People living with chronic liver diseases
  • People living with HIV
  • adults with diabetes ages 19–59 years (at the discretion of clinicians
  • for people with diabetes aged 60 and older)
  • People who are incarcerated
  • Anyone over the age of 60 who wants to be vaccinated.

If a person already has HBV, vaccination offers no protection against disease progression or risk of liver disease. Check for immunity or chronic infection before getting vaccinated. 

Most people will clear HBV naturally and achieve immunity. Treatment for HBV is called for in anyone with cirrhosis, regardless of ALT or HBV viral load. Similarly, anyone living with chronic HBV who is undergoing immunosuppressive therapy should be treated to prevent an HBV flare-up. There are other scenarios where a person should be treated.