Why Do Babies Need the Hepatitis B Vaccine?
January 29, 2026
Bringing a new baby into the world comes with a lot of decisions - especially when it comes to protecting their health. One of the first and most important steps is the Hepatitis B (Hep B) vaccine, which is recommended within the first 24 hours after birth.
What is Hep B?
Hep B is a contagious liver infection caused by the Hepatitis B Virus (HBV). It spreads through infected blood and bodily fluids like saliva and can cause either a short-term (acute) illness or a lifelong (chronic) infection. Chronic Hep B can lead to serious health problems later in life, including liver damage, cirrhosis or liver cancer.
Most people with chronic hepatitis do not have symptoms, but the disease can cause serious liver damage, liver cancer and death. As such, many people who carry the virus don’t feel sick and may not know they’re infected—but they can still pass it on to others. Children infected at birth or in early childhood are 90% more likely to develop chronic Hep B than adults.
There is a vaccine to prevent Hep B, and newborns should get it as soon as possible – ideally within the first 24 hours of life as they could be exposed to the virus during birth or shortly after coming home, from family members or other caregivers. Most people who get vaccinated against Hep B are immune for life. The vaccine is over 95% effective at preventing this disease in children and adults.
How does Hep B spread?
Hep B spreads when blood or body fluids from an infected person enter the body of someone who isn’t infected. The virus can survive for up to seven days in dried blood particles on surfaces and objects including personal items people use regularly and sometimes share.
People can become infected with Hep B through:
Birth (if a pregnant person has Hep B, their baby can become infected)
Sharing items such as razors or toothbrushes with an infected person
Contact with blood, open sores or saliva with traces of blood of an infected person
Sex with an infected partner
Exposure to blood from needlesticks or other sharp tools, including tattoo or piercing needles that were not properly sanitized
Why is the Hep B vaccine important for babies?
Babies who become infected at birth or in early childhood are much more likely to develop chronic Hep B than adults. In fact, about 9 out of 10 infants infected at birth will develop a lifelong infection.
Giving the first dose of the Hep B vaccine within the first 24 hours of life provides a crucial layer of protection. It acts as a safety net in case a baby is exposed to the virus during birth or shortly after coming home—often from someone who doesn’t know they’re infected. The vaccine helps a baby’s immune system recognize and fight the virus before it can cause harm.
Is the Hep B vaccine safe and effective?
Yes. The Hep B vaccine has been used for decades and is over 95% effective at preventing infection in both children and adults. Most people who complete the vaccine series are protected for life.
When are the Hep B shots given?
The Hep B vaccine is given in three doses:
First dose: Within 24 hours after birth
Second dose: At 1–2 months of age
Third dose: Between 6 and 18 months of age
Once all three doses are complete, most children are considered fully protected for life.
The bottom line
The Hep B vaccine is one of the earliest ways parents can protect their baby from a serious but preventable disease. By starting the vaccine at birth, you’re giving your child strong, long-lasting protection right from the very beginning.
