For U.S. newborns, the Hepatitis B series is 3 doses — birth, 1–2 months, and 6–18 months; a 4th dose may be given when combo shots are used.
New parents ask this a lot in the first day or two after delivery. Hepatitis B can pass during birth, so the first shot at the hospital is standard in the United States. From there, the schedule finishes across the first year of life. Below is a clear map of how many doses a newborn needs, when each dose happens, and the few situations that change the count.
Dose Count At A Glance
Most babies in the United States get three Hepatitis B shots. The first comes at birth, the second at 1–2 months, and the third at 6–18 months. That completes the series. Some babies receive four total doses when the birth shot is followed by combination vaccines at later visits. A four-dose path is fine and safe, and many clinics use it. See the CDC child immunization schedule for the full age map.
Newborn HepB Dosing Scenarios In The U.S.
Here’s a quick reference that lays out the common birth room situations, what happens right away, and how many HepB shots that path adds up to by the end of the series.
| Newborn Scenario | What Happens At Birth | Total HepB Doses |
|---|---|---|
| Parent HBsAg negative, birth weight ≥ 2,000 g | One monovalent HepB shot within 24 hours | 3 |
| Parent HBsAg negative, birth weight < 2,000 g | First HepB shot at age 1 month or at discharge | 3 |
| Parent HBsAg positive (any weight) | HepB shot + HBIG within 12 hours; complete series | 3 (or 4 if <2,000 g at birth) |
| Parent HBsAg unknown at delivery | Give birth dose within 12 hours; add HBIG if parent later tests positive | 3 (or 4 if combination vaccines used) |
| Clinic uses combination vaccines after birth dose | Birth dose is monovalent; later combo shots include HepB | 4 |
Why The Birth Dose Matters
The birth dose acts as a safety net. Parents can arrive with unknown test results, records can lag, and a fast dose lowers the chance of passing the virus during or soon after delivery. The shot used at birth is a single-antigen vaccine, not a combination. Babies then move to the next doses at routine well-child visits.
When The Parent Tests Positive For Hepatitis B
If the birth parent’s lab shows HBsAg positive, the baby needs two things within 12 hours: the standard HepB shot and a separate injection of hepatitis B immune globulin (HBIG). That mix protects the infant while the vaccine series teaches long-term defense. The baby still completes the series on schedule. If the infant weighs under 2,000 grams, the birth dose does not count toward the three-dose series, so the total number of HepB shots becomes four. Clinicians later check antibodies per CDC perinatal page.
When The Parent’s Status Is Unknown At Delivery
Give the birth dose within 12 hours while the test result is pending. If the result later comes back positive, the infant should also receive HBIG as soon as possible, up to seven days of age. If the result is negative, the baby continues with the routine series. Many hospitals run this plan as standard work so no infant leaves without a first shot.
Preterm And Low Birth Weight Newborns
Babies under 2,000 grams can have a weaker response to a vaccine dose given in the first day of life. If the parent is HBsAg negative, the first HepB shot is given at age one month or at hospital discharge, whichever comes first. If the parent is positive, the infant still receives the birth dose and HBIG within 12 hours; in that case the birth dose is not counted, and the infant completes three more doses for a total of four.
Close Variation: How Many Hepatitis B Shots For A U.S. Newborn — Dose Guide
Across routine care, a U.S. newborn receives a three-dose HepB series. The birth dose is monovalent. Later visits may use a combination vaccine that includes HepB along with other routine shots, which raises the count to four. Both paths reach the same goal: strong, durable protection in early life.
Minimum Intervals And Timing Rules
Spacing rules keep the series on track. Dose two must be at least four weeks after dose one. Dose three must be at least eight weeks after dose two and at least sixteen weeks after dose one. The last dose should not be given before twenty-four weeks of age, even if earlier dates seem to fit.
HepB Minimum Intervals And Earliest Ages
Use this timing guide when scheduling or catching up. It reflects ACIP rules used by U.S. clinics and health departments.
| Dose | Minimum Timing | Notes |
|---|---|---|
| 1 (birth) | Given within 24 hours of delivery | Monovalent vaccine at a separate site from HBIG if used |
| 2 | ≥ 4 weeks after dose 1 | Can be part of a combination vaccine at age ≥ 6 weeks |
| 3 (final) | ≥ 8 weeks after dose 2 and ≥ 16 weeks after dose 1 | Do not give before 24 weeks of age |
Post-Vaccination Testing For Babies Exposed At Birth
Infants born to an HBsAg-positive parent need a lab check after finishing the series. Clinicians order HBsAg and anti-HBs at nine to twelve months of age, or one to two months after the last dose if the series was delayed. This step confirms protection and checks for infection picked up around delivery. Most infants show protective antibodies.
What If A Dose Was Missed?
Start where the baby left off. The series never restarts. Use the minimum intervals to plan the remaining dates. Many clinics catch up with a combination vaccine that includes HepB along with DTaP, IPV, or Hib, which can bring the total count to four. The end point remains the same: three valid HepB doses spaced by the rules, with a fourth allowed when a combo shot is used.
Safety And Side Effects In Newborns
The HepB shot has a long track record in nursery care. The most common reactions are a sore thigh or a mild fever. Serious reactions are rare. The vaccine can be given with other routine newborn care steps, including vitamin K and eye ointment. Nurses place the birth dose in a different site from HBIG when both are used.
Talking With Your Care Team
If anything about the schedule is unclear, ask the nurse or pediatrician on the unit. They can show the dates in your child’s record and note any special steps based on lab results or birth weight. Before discharge, check that the first shot was documented and that the next visit is booked.
Practical Tips For Parents
Bring the shot card to every visit. Keep a phone photo of the card as backup. Ask which product your child received at birth; later visits may use a different product in a safe, planned way. Place calendar reminders for the one- to two-month visit and for the six- to eighteen-month window so the last dose lands at or after twenty-four weeks of age.
Home Births And Out-Of-Hospital Delivery
If you plan a home birth or a free-standing birth center, set up the HepB birth dose in advance. A licensed midwife or the baby’s clinic can supply the vaccine and HBIG if needed. The timing stays the same: give the birth dose within the first 24 hours, and add HBIG within 12 hours when the parent is HBsAg positive. If supply delays the shot, go to a clinic or hospital that day for the dose.
Keeping Track Across Clinics And Moves
Families sometimes move or switch providers during the first year. Ask for a copy of the shot record at each visit and store a photo of it on your phone. Most states use immunization registries that let clinics see prior doses. Bring the birth paperwork to the first office visit so the team can confirm the brand and dose date entered by the hospital. Keep copies in a safe place.
What To Ask Before Discharge
On the last day in the hospital, run through a list with your nurse. Confirm that the birth HepB dose is documented, that you know the parent’s HBsAg result, and that the next appointment is scheduled. If HBIG was given, ask the clinic to place a reminder for the nine- to twelve-month lab check. These small steps prevent mix-ups later and keep the series on a smooth timeline.
Why Some Babies Receive Four Total Doses
After the monovalent birth dose, many practices switch to a combination vaccine at two and four months. That combo includes HepB along with other routine shots. The baby then still needs the final HepB dose at six months or later. This path creates a four-dose HepB count, which meets the series rules and is common across the country.
Special Testing Milestones After Perinatal Exposure
For babies who received HBIG at birth, the antibody check at nine to twelve months is the final milestone. If anti-HBs is low after a single extra dose, two more doses are given, followed by repeat labs. Your clinician follows a standard algorithm for that decision tree.
Takeaways For U.S. Newborn HepB Doses
Three doses finish the job for most newborns, with the birth shot starting the clock. Four total doses appear when a clinic uses a combination vaccine for the middle visits or when a low-birth-weight infant needs an extra dose. Staying on schedule keeps your child protected through the first year for families.