How much immunity does the first Hepatitis B vaccine shot provide?

One Dose Not Enough. Hepatitis B virus occurs world wide; is a cause of serious liver disease; is transmitted thru blood/body fluids. Immunization is effective for prevention & post-exposure management. Vaccination after 2 doses provides protection in up to 80% of recipients and protects 90-95% after 3 doses. Blood test to confirm immunity after vaccination recommended for certain risk groups. Discuss with doctor.