What Is the Hepatitis B Vaccine?

The hepatitis B vaccine (HepB) protects against hepatitis B, a liver infection caused by the hepatitis B virus. People who get infected can have no symptoms, or they can have a mild illness that feels like the flu. Some can be sicker with fever, nausea, vomiting, and jaundice that lasts for a few weeks.

When Do People Get the HepB Vaccine?

Kids usually get the hepatitis B vaccine (HepB) as a series of 3 shots:

1. shortly after birth
2. at 1–2 months of age
3. at 6–18 months of age

For the first shot:

• If a newborn's mother carries the hepatitis B virus in her blood, the baby must get the vaccine within 12 hours after birth. The baby also needs another shot — hepatitis B immune globulin (HBIG) — to provide protection against the virus right away. If the baby had a low birth weight (less than 2000 grams or 4 pounds, 7 ounces), they'll need to get the 3 routine doses in addition to this first shot starting at 1 month of age, for a total of 4 doses.
• If a newborn's mother doesn't have the virus in her blood, the baby can get the HepB vaccine within 24 hours after birth. If the baby had a low birth weight, they'll wait to get first dose at 1 month of age or when they're discharged from the hospital (whichever comes first), for a total of 3 doses.

Anyone under age 60 should get the vaccine series at any time if they missed it as a baby. Adults 60 years or older should get the vaccine if they are at higher risk of getting infected, or if they simply would like to be protected from the virus.

Some kids may need to get vaccinated again later in life. These include children:

• whose mothers carry the hepatitis B virus in their blood
• who need hemodialysis
• who have a weak immune system

Sometimes doctors give the HepB vaccine in combination (in the same shot) with other vaccines, such as DTaP, IPV, Hib, or HepA vaccines.

Why Is the HepB Vaccine Recommended?

People who don’t know they're infected can spread the hepatitis B virus. So it can’t be avoided just by being careful. That's why health experts recommend that all babies get the vaccine right from birth.

The HepB vaccine usually creates long-term immunity. Most infants who get the HepB series are protected from hepatitis B infection beyond childhood, into their adult years.

Protecting from hepatitis B infection also decreases risk for cirrhosis of the liver, chronic liver disease, and liver cancer.

What Are the Possible Side Effects of the HepB Vaccine?

Side effects usually are mild, and can include a low fever, headache, tiredness, loss of appetite,  and soreness or redness at the injection site. As with any vaccine, there is a small risk of fainting, and a very small chance of an allergic reaction.

The HepB vaccine contains a killed (inactivated) virus, so it can't cause hepatitis.

When to Delay or Avoid the HepB Vaccine

Doctors delay giving the vaccine to babies who weigh less than 4 pounds, 7 ounces (2,000 grams) at birth whose mothers do not have the virus in their blood. The baby will get the first dose at 1 month of age or when the baby is discharged from the hospital.

Simple colds or other minor illnesses should not prevent vaccination. Your doctor might reschedule the vaccine if your child has a more serious illness.

Talk to your doctor about whether the vaccine is a good idea if your child has ever had a serious allergic reaction, or any allergic reaction after an earlier dose of the vaccine or to baker's yeast.

Caring for Your Child After HepB Immunization

For pain or fever, check with your doctor to see if you can give either acetaminophen oribuprofen, and to find out the right dose.

A warm, damp cloth or a heating pad on the site of the shot may help reduce soreness, as can moving or using the arm or leg.

When Should I Call the Doctor?

Call the doctor if:

• You're not sure of the recommended schedule for the HepB vaccine.
• You have concerns about your own hepatitis B carrier state.
• Your child has moderate or serious side effects after getting a HepB shot.