When your baby is born, the immune system begins learning right away how to protect against new germs and viruses in the surrounding environment. Vaccines contribute to that process by safely teaching the immune system how to defend against serious infections—starting with hepatitis B.
The hepatitis B vaccine is usually the first vaccine a child receives, often within the first 24 hours of life. This timing is intentional and supported by decades of research showing that early protection can prevent lifelong infection from hepatitis B, a serious virus that can lead to chronic disease and liver failure.
Since the birth-dose recommendation began in 1991, hepatitis B infections in infants have dropped by about 95 percent in the United States, preventing more than 500,000 childhood infections. This is considered a major public health success.
What Is Hepatitis B?
Hepatitis B is a viral infection that attacks the liver. While some people clear the virus on their own, infants and young children are far more likely to develop chronic (lifelong) infection if they are exposed.
In fact, up to 9 out of 10 babies who become infected with hepatitis B will develop chronic hepatitis.
Because serious complications often don’t appear until young adulthood, hepatitis B is sometimes called a “silent” disease. Once the disease progresses, it can lead to:
- Liver inflammation and damage
- Cirrhosis (scarring of the liver)
- Liver failure
- Liver cancer
How Is Hepatitis B Spread?
There’s a common misconception that hepatitis B is only spread through sexual contact. In reality, the virus is spread through blood and certain body fluids, meaning exposure can happen in everyday situations, especially for infants.
Importantly, many people with hepatitis B have no symptoms and don’t know they’re infected, which means transmission can occur unknowingly.
Hepatitis B can be passed to a baby:
- During childbirth, if a mother has hepatitis B and doesn’t know it
- Through contact with infected blood or body fluids from any other caregivers, family and friends
The virus is surprisingly resilient and therefore highly contagious. It can survive on surfaces for up to seven days, meaning exposure can happen through shared household items such as:
- Toothbrushes
- Nail clippers
- Items contaminated through small cuts or scrapes
Because infants explore the world with their hands and mouths, preventing early exposure with vaccines is the best way to keep them safe.
Why Is the Hepatitis B Vaccine Given at Birth?
Giving the hepatitis B vaccine at birth provides infants with protection before any exposure can occur.
The benefits of vaccinating against Hep B at birth include:
- Acting as a safety net if a mother has hepatitis B but is unaware
- Protecting babies during a vulnerable period when infection is most dangerous
- Helping to prevent household or accidental exposure in early life
How Effective Is the Hepatitis B Vaccine?
The hepatitis B vaccine is highly effective. After completing the full vaccine series, about 98 percent of children develop long-lasting immunity.
Protection often lasts for decades, and possibly for life. This means a few early doses can help prevent serious liver disease many years down the road.
Is the Hepatitis B Vaccine Safe for Babies?
Yes. The hepatitis B vaccine has been used for decades and is one of the most carefully studied childhood vaccines.
The vaccine does not contain live virus and cannot cause hepatitis B. It’s safe for newborns, including premature infants. Most babies have no side effects or only mild ones, such as temporary soreness at the injection site.
When Do Children Receive the Hepatitis B Vaccine?
The standard hep B vaccine schedule, which is designed to provide early protection and long-term immunity, includes:
- First dose: At birth (ideally within 24 hours, when possible)
- Second dose: At 1-2 months of age
- Third dose: At 6-18 months of age
Why Pediatricians Strongly Recommend the Birth Dose
Pediatricians see firsthand the long-term consequences of hepatitis B infection, and also see how effective prevention and vaccination can be.
Missing the birth dose doesn’t just delay protection; it leaves infants vulnerable during the time when hepatitis B infection is most likely to become chronic and life-threatening.
Choosing the hepatitis B vaccine at birth is a simple, powerful step that helps protect your child’s future health.
At Stony Brook Children’s Hospital, our pediatricians are committed to helping families make informed, confident decisions about their children’s health. We understand that parents may have questions about vaccines, and we welcome those conversations.
Our goal is always the same: to protect children from preventable illness and set them up for a healthy future. If you have questions about the hepatitis B vaccine or your child’s immunization schedule, your pediatric care team is here to help guide you every step of the way.
