Has the time frame changed from 6 to 4 months for the Hep B series?

For the basin hepatitis B vaccine series, there should be 3 doses. The second dose should be given one month after the first dose. The third dose should be given at least two months after the second dose (and at least four months after the first dose). An easy way to think of this is day 1, then a month later, then 5 months later. There is sometimes confusion because there is some flexibility regarding the exact timing of the 3rd dose.

If the combined hepatitis A and hepatitis B vaccine is used, it should be given at 0, 1, and 6 months. An accelerated schedule is also fine, but requires a 4th dose: days 0, 7, and 21 followed by a booster dose at month 12.

Adults receiving hemodialysis or with immunosuppressed states should receive 1 dose of 40 mcg/mL (Recombivax HB) administered on a three-dose schedule at 0, 1, and 6 months or 2 doses of 20 mcg/mL (Engerix-B) administered simultaneously on a four-dose schedule at 0, 1, 2, and 6 months.