Blood Tests

HBV screening is important! Most chronically infected persons show no outward signs of HBV infection, therefore screening for hepatitis B is necessary to:

  • Identify individuals who have chronic HBV infection so they can receive appropriate medical management.
  • Identify those who are unprotected so they can be vaccinated.
  • Avoid unnecessary vaccination and help reduce costs.  Vaccination is not beneficial for patients already chronically infected with HBV or already immune (either through prior vaccination or a previous resolved acute infection).


HBV screening is a simple blood test for the following markers:

1. Hepatitis B surface antigen (HBsAg)
The HBsAg test is the ONLY way to definitively diagnose chronic HBV infection.  By definition, if you remain HBsAg-positive for more than 6 months, then you have developed chronic (lifelong) infection. 

2. Hepatitis B surface antibody (anti-HBs)
The anti-HBs test will tell you if you are protected against HBV.  Anti-HBs can be produced in response to vaccination or recovery from an acute hepatitis B infection.



HBsAg (+)
anti-HBs (-)

Chronic HBV infection *

HBsAg (-)
anti-HBs (+)

Immune to HBV

HBsAg (-)
anti-HBs (-)

Unprotected; need vaccination

HBsAg (+)
anti-HBs (+)

Chronic HBV infection *

* If HBsAg remains positive for 6 months

Who should get screened for HBV?

2006 guidelines from the Centers for Disease Control and Prevention (CDC) call for routine HBV screening of all foreign-born persons from high endemic areas (see box below) regardless of their immunization history.  This includes immigrants, refugees, asylum seekers, and internationally adopted children.

  • Although a safe and effective recombinant hepatitis B vaccine has been available since 1986, HBV still kills 700,000-1 million people every year worldwide.
  • About 1in 20 people in the world (370 million individuals) are living with chronic HBV infection.
  • Without appropriate monitoring or treatment, 1 in 4 of those chronically infected will die from liver cancer or liver failure.
  • Every 30-45 seconds, one person dies from this vaccine-preventable disease.

The CDC recommends routine HBV screening for all persons born in high endemic regions (HBsAg prevalence of ≥8%):

  • Africa
  • Asia and Pacific Islands
  • Carribean (Turks and Caicos)
  • Eastern Europe
  • Middle East (Saudi Arabia and Jordan)
  • America (Amazon Basin)
  • Alaska, Northern Canada, and Greenland (indigenous populations)

Other groups recommended for HBV screening include:

  • Household, sex, and needle-sharing contacts of HBsAg-positive persons
  • Pregnant women
  • HIV-infected persons
  • Hemodialysis patients


Where can I get tested

If you are a resident in the Bay Area in California, there are several free or low-cost screening and vaccination programs.

Pacific Free Clinic in Silicon Valley: 1835 Cunningham Ave., San Jose, CA 95122

  • Saturdays from 10 AM – 2 PM
  • Overfelt High School
  • Screenings and vaccinations are free
  • Only for people with no health insurance


San Francisco Hep B Free

  • San Francisco Hep B Free is a citywide campaign to turn San Francisco into the first hepatitis B free city in the nation
  • Free and low-cost hepatitis B testing and vaccinations
  • For all locations:

The Hep B Project

  • Wednesdays from 1:30 – 4 PM at 2501 International Blvd, Oakland, CA inside Street Level Health Project
  • Saturdays from 10 – 11:20 AM at 818 Webster Str, Oakland, CA inside Asian Health Services
  • Screenings and vaccinations are free
  • Only for people with no health insurance














If you know of any other free or low-cost screening and vaccination sites throughout the country, please contact us, and we will add the information this website!