Prescribe the adult hepatitis B vaccine series (Engerix‑B [hepatitis B vaccine] 20 µg 1 mL intramuscularly) for a new adult patient, including the dose amounts and the correct intervals (dose 1 today, dose 2 in 1 month, dose 3 in 6 months).

Hepatitis B Vaccine Prescription for Unvaccinated Adult

Prescribe Engerix-B (hepatitis B vaccine) 20 µg/1.0 mL intramuscularly for three doses: the first dose today, the second dose in 1 month, and the third dose 6 months after the first dose. 1, 2, 3

Standard Adult Dosing Regimen

• The CDC recommends all adults aged 19–59 years receive hepatitis B vaccination, removing the previous requirement for risk factor assessment. 1 This patient qualifies for universal vaccination regardless of occupational indication.

• For adults ≥20 years, administer Engerix-B 20 µg (1.0 mL) intramuscularly in the deltoid muscle at months 0,1, and 6. 2, 4, 3 The deltoid is the preferred site; gluteal injection results in suboptimal response. 3

• Alternative acceptable vaccines include Recombivax HB 10 µg (1.0 mL) at 0,1,6 months or Heplisav-B 20 µg (0.5 mL) at 0 and 1 month (2-dose series only). 2, 4 However, Engerix-B is the most widely used standard formulation.

Prescription Details

Write the prescription as follows:

• Medication: Engerix-B (hepatitis B vaccine, recombinant) 20 µg/1.0 mL
• Route: Intramuscular (deltoid muscle)
• Dose 1: Administer today (month 0)
• Dose 2: Administer in 1 month (minimum 4 weeks after dose 1) 2, 3
• Dose 3: Administer 6 months after dose 1 (minimum 8 weeks after dose 2 AND minimum 16 weeks after dose 1) 2, 3
• Dispense: Three 1.0 mL single-dose vials or prefilled syringes 3

Expected Immunogenicity

• This standard 0-1-6 month schedule produces seroprotection (anti-HBs ≥10 mIU/mL) in 79% of adults by month 6 and 96% by month 7, with a geometric mean titer of 2,204 mIU/mL among responders. 3

• Seroprotection rates decline with age: >95% in adults <40 years but only 75% in adults ≥60 years. 4 Additional factors reducing response include smoking, obesity, and immunosuppression. 4

Critical Administration Points

• Use a 1-inch, 23-gauge needle for deltoid injection in adults. 3 Never administer in the buttock, as this substantially reduces immunogenicity. 2, 3

• Shake the vial well before each dose; the vaccine should appear as a slightly turbid white suspension. 3 Discard if particulate matter, discoloration, or cracks are present. 3

• Minimum intervals must be respected: 4 weeks between doses 1 and 2,8 weeks between doses 2 and 3, and 16 weeks between doses 1 and 3. 2, 4 Doses given ≤4 days before the minimum interval are considered valid. 2, 4

Management of Interrupted Series

• If the patient misses an appointment, do not restart the series—simply continue where left off. 2, 4 There is no maximum interval between doses. 2

• If dose 2 is delayed, administer it as soon as possible, then give dose 3 at least 8 weeks later and at least 16 weeks after dose 1. 2

Post-Vaccination Testing

• Routine serologic testing is not required for healthy adults. 4 However, if this patient is a healthcare worker with blood exposure risk, test anti-HBs 1–2 months after the third dose to confirm protective levels ≥10 mIU/mL. 2, 4

Common Pitfalls to Avoid

• Never restart the series if interrupted; this wastes doses and delays protection. 2, 4

• Never give the third dose before 16 weeks from the first dose, even if 8 weeks have passed since the second dose. 2, 4

• Never inject in the gluteal region in adults, as this results in suboptimal immune response. 2, 3

• Do not use Heplisav-B or PreHevbrio if the patient is pregnant, on hemodialysis, or immunocompromised; use Engerix-B or Recombivax HB instead. 2, 4