For the newborn hepatitis B vaccine in the USA, the standard volume is 0.5 mL of a single-antigen HepB shot given intramuscularly at birth.
Why Dose Matters On Day One
Clinicians see this question in delivery units daily. The order set is packed, nurses move fast, and families ask what that small syringe holds. The answer is steady: the birth dose is a half milliliter. That 0.5 mL of monovalent hepatitis B vaccine starts protection right away and keeps babies on track for the full series. The shot pairs with hepatitis B immune globulin for exposures.
U.S. policy calls for a birth dose for every infant. That timing reduces missed cases when a parent’s infection status is unknown or recorded late. Standing orders close gaps. The volume is the same across products used in nurseries: a single 0.5 mL dose.
| HBsAg-positive parent, infant ≥2,000 g | Give HepB 0.5 mL and HBIG within 12 hours, separate limbs | Finish series on time; do post-vaccination serology at 9–12 months |
| HBsAg-positive parent, infant <2,000 g | Give HepB 0.5 mL and HBIG within 12 hours; birth dose doesn’t count | Give three more HepB doses for a total of four; do serology at 9–12 months |
| HBsAg status unknown, infant ≥2,000 g | Give HepB 0.5 mL within 12 hours; test the parent | If parent is positive, give HBIG as soon as possible, no later than 7 days |
| HBsAg status unknown, infant <2,000 g | Give HepB 0.5 mL and HBIG within 12 hours | Manage as exposed until status returns |
| HBsAg-negative parent, infant ≥2,000 g | Give HepB 0.5 mL within 24 hours of birth | Complete the series at 1–2 months and 6–18 months |
| HBsAg-negative parent, infant <2,000 g | Defer HepB until age 1 month or discharge | Then follow the routine series |
ML Dose Of Hepatitis B Vaccine For Newborns In The U.S. — Practical Rules
Dose volume is not guesswork in newborn care. The pediatric presentation of Engerix-B contains 10 micrograms per 0.5 mL, and Recombivax HB contains 5 micrograms per 0.5 mL. Either product meets U.S. guidance for the birth dose when used as a single-antigen vaccine. Combination vaccines are not used for the birth injection.
Give the shot intramuscularly in the anterolateral thigh. For a neonate, a 22–25 gauge, 5⁄8-inch needle reaches the vastus lateralis safely. Infants older than a month usually need a 1-inch needle for the same site. Use different limbs for HepB and HBIG when both are indicated.
Timing matters for uptake. Aim for the birth dose within 24 hours for all infants before discharge. When the parent is HBsAg-positive or status is unknown at delivery, act by 12 hours and add HBIG. That window delivers the best protection against perinatal transmission.
For product names, dose schedules, and exact steps, see CDC perinatal guidance and the needle length chart used by vaccinators. Package inserts for Engerix-B and Recombivax HB show the same 0.5 mL pediatric volume.
The newborn dose isn’t weight-based and never needs conversion. Whether a baby weighs 2.6 kg or 4.1 kg, the volume stays at 0.5 mL. Brands differ in micrograms, yet clinical guidance treats them as interchangeable for healthy infants at birth. Use only the monovalent vial or prefilled syringe in the delivery unit, then bring in combination products later to limit needle sticks during clinic visits.
Dosing Schedule After The Birth Shot
Healthy term infants complete a three-dose series. After the birth shot at day 0, the next doses fall at 1–2 months and again at 6–18 months. Nurseries often schedule dose two around the first well-baby visit. Pediatric clinics decide the exact month for the third dose based on the products used with other routine vaccines.
Combination vaccines join the lineup after the hospital stay. Pediarix and Vaxelis both include hepatitis B antigen and can help reduce injections in clinic. Neither is used for the birth injection. Use one brand for consistency when possible, but it is acceptable to complete the series with available products.
For infants who received HBIG because the parent was HBsAg-positive, order post-vaccination serology at age 9–12 months. Check HBsAg and anti-HBs to confirm protection and rule out infection acquired at delivery. If anti-HBs is less than 10 mIU/mL, follow the action steps in your local protocol for additional doses and repeat testing.
Special Situations In The Nursery
Preterm infants under 2,000 grams who are born to an HBsAg-negative parent wait until age 1 month or discharge for their first HepB dose. The smaller mass changes muscle depth and antibody kinetics, so waiting improves response. When the parent is positive or status is unknown, give vaccine and HBIG within 12 hours, and do not count the birth injection toward the three-dose count.
If a baby’s weight is just under the 2,000-gram mark, teams sometimes ask whether a dose at 48 hours fits the rule. Follow the same approach: give vaccine plus HBIG within 12 hours if exposure is possible. If not exposed and the parent tested negative, start at 1 month or at discharge when weight and feeding are stable.
If clerical work delays the parent’s HBsAg result, treat the infant as if the status is unknown and start protection on time. When the lab report arrives, add HBIG if the parent is positive. If the parent is negative, the first dose stands and the rest of the series proceeds on the usual timetable.
Common Administration Details
Site And Technique
Preparation is standard for intramuscular infant shots. Use alcohol to clean the site, allow it to dry, and stretch the skin to create a firm surface. Insert the needle at 90 degrees, inject the full 0.5 mL, then withdraw and apply gentle pressure. Do not massage the site. Document brand, lot, site, time, and the Vaccine Information Statement given to the parent or guardian.
Storage
Store vaccine at the temperature listed on the label and do not freeze. Check lot numbers and expiration dates during the med pass and during inventory work at shift change. If storage is interrupted, use the manufacturer’s vaccine management line to assess viability before discarding stock. Keep backup stock logged and alarms tested each shift. Each unit should keep a quick checklist near the medication fridge posted.
When HepB And HBIG Are Both Needed
When a baby needs both HepB and HBIG, choose opposite thighs. Label the limbs on the newborn flowsheet so the night team can audit placement. HBIG volume varies by product, and it should not mix in the same syringe with vaccine.
Common Reactions And Counseling
Local redness, swelling, or fussiness can show up in the first day. A low-grade fever is possible. Parents can hold and feed through routine discomfort. Serious allergic events are rare, and teams respond quickly if any concerning signs appear in the unit. Nursery teams can suggest skin-to-skin, swaddling, and brief feeds for comfort, and acetaminophen only if a clinician advises.
Parents often ask why a baby needs hepatitis B protection so early. The short answer is reliability. A birth dose catches silent maternal infection, guards against equipment exposures, and anchors the full series. Families leave with a head start on long-term protection.
Product Options And Dose Details
Two single-antigen vaccines are used from birth in the United States. Both deliver a 0.5 mL pediatric dose. The antigen content differs by brand, yet the newborn volume is the same. Combination products enter later visits to streamline care.
| Engerix-B (GSK) | 0.5 mL; 10 μg HBsAg | Used at birth; single-antigen only |
| Recombivax HB (Merck) | 0.5 mL; 5 μg HBsAg | Used at birth; single-antigen only |
| Pediarix or Vaxelis | Dose per label; combo products | Not for the birth injection; start at later visits |
Error Prevention And Fixes
Dose errors are uncommon when order sets are clear. If a pediatric dose was given subcutaneously by mistake, contact your pharmacy lead and review CDC guidance for next steps. If a nurse used an adult 1 mL dose in a newborn, count that dose as valid and counsel the family about expected local soreness.
If a baby missed the shot before discharge, schedule an urgent nurse visit for the first week. When a parent declines during the birth stay, revisit the decision with respectful counseling and offer the dose in clinic as soon as possible. If HBIG was indicated but delayed, arrange it within seven days and notify the pediatrician.
What This Means For Teams
Keep the 0.5 mL rule front and center on newborn order sets and whiteboards. Confirm HBsAg results early, but never delay the birth dose while waiting on a chart update. Track every birth dose on a dashboard so missed cases trigger same-week outreach.
The answer to the headline question is crisp and repeatable. For newborns in the United States, the hepatitis B vaccine is given as 0.5 mL of a single-antigen product in the thigh at birth. That volume, paired with timely steps, gives each baby a strong start today nationwide.