Hepatitis B Vaccine: The Importance of the Birth Dose

babiesDid you know that Saturday kicked off National Infant Immunization Week, which is part of a worldwide observance that shines the spotlight on the importance of vaccination? Most of us think of infant immunization as a tool to protect babies from childhood illnesses like chickenpox and whooping cough. But did you know that one infant immunization protects them from cancer later in life?

Globally, hepatitis B virus (HBV) is one of the top causes of cancer. Every year, it kills more than three-quarters of a million people worldwide. An HBV infection might be defeated by the immune system, but when it’s not, it can become a chronic infection. And chronic infections can lead to serious health outcomes, including cirrhosis and liver cancer. The younger you are, the less likely you’ll be able to fight off an HBV infection — 90 percent of infants infected with HBV will develop chronic infections, and 25 percent of them will go on to die prematurely after developing liver disease. Compare that to 2 to 6 percent of infected adults who will develop chronic infections.

Because infants are so vulnerable to developing chronic infections, vaccinating them against hepatitis B at birth makes sense.

Most people think of hepatitis as a bloodborne disease, and it is spread very efficiently when IV drug users share needles, during needle-stick accidents and other occupational injuries, or by using contaminated piercing needles, tattoo equipment, or acupuncture needles. Even sharing items like razors, toothbrushes, and nail clippers can do it, as the virus can survive outside of the human body for a week. HBV can also be spread by sexual contact, including vaginal and anal sex.

Lastly, babies and children can be at risk as the virus can be transmitted from mother to infant during birth, and during early childhood when risk of chronic infection is high. A significant number of people with chronic infections acquired them during early childhood, but we don’t know exactly how they got them, as their parents and other household contacts were negative for the virus or its antibodies. Since infants and children are at the highest risk for developing chronic infections, focusing on that population for prevention is very important.

Luckily, there’s a vaccine. It debuted in the early 1980s, but at first, it was offered only to people considered to be at highest risk for HBV, such as drug users, health-care workers, and babies born to mothers carrying HBV. That targeted approach didn’t seem to have the desired effect on new HBV cases. In response, recommendations changed in 1991: All infants would receive the vaccination series, beginning with the birth dose, which would be administered soon after delivery. In the United States, new cases of HBV infection have plummeted by 82 percent — and between 1990 and 2004, new infections decreased by 94 percent among people 20 years of age and under. We now recognize that this sort of mass-vaccination strategy will enable us to eradicate the disease from the planet.

HBV line graphCurrent recommendations state that the birth dose is to be administered within 12 hours of birth when the mother is a carrier of HBV, or when her status is unknown — all other babies should receive the shot before hospital discharge. Currently, around 72 percent of U.S. infants receive the shot within the first two days of life. In Arizona, we’re actually doing better than average, with around 77 percent of our babies vaccinated in that time period. We can do better, though!

The birth dose is endorsed by leading health and professional organizations: the Centers for Disease Control and Prevention, the American Academy of Pediatrics, the American Academy of Family Physicians, and the American College of Obstetricians and Gynecologists. Yet, with all this support, a lot of parents question why their baby would need a vaccine to protect them against a virus that they associate with sex and drugs.

The names and results of hepatitis B screening tests can be confusing.

There are many compelling reasons to initiate the vaccination series soon after birth. First, administering the vaccine to babies born to mothers who are carriers is a no-brainer: The vaccine, plus a shot of immune globulin, will reduce infection risk by around 95 percent, during a crucial time period when the infant is the most vulnerable to developing a chronic infection.

Second, even when a mother is not known to be a carrier for the virus, universal administration of the birth dose acts as a safety net. Errors do occur, and some of the most common errors include ordering the wrong screening test for a pregnant person, or misinterpreting or even mistranscribing the results. As you can see, the names of HBV tests can be very similar, sometimes differing by only one letter.

Initiating the vaccination series at birth also dramatically increases the chances that the infant will complete the immunization process, and might even increase their chances of receiving other important childhood vaccinations. While the vaccine probably provides lifelong protection, we have solid evidence that the vaccine provides protection for at least 20 years, covering the time period during which a child is most vulnerable to developing a chronic infection.

And those years are critical. Since so many early childhood infections occur with no known mode of transmission, early vaccination will protect a child if he or she encounters this hardy virus during daily life. In developed nations, 30 to 40 percent of chronic carriers acquire the virus before their 5th birthday, and before universal vaccination began in 1991, an estimated 16,000 children per year acquired the virus before turning 10, but after they were newborns.

Hepatitis B vaccine is safe and effective. Given how dangerous HBV is, eradicating it should be one of our top priorities — and, because there are no non-human carriers of this virus, mass vaccination can allow us to wipe HBV off the planet. Administering the birth dose will protect babies at birth and throughout their childhood, during their most vulnerable years, and will almost certainly continue to protect them throughout the rest of their lives. Put simply, the birth dose saves lives!

2 thoughts on “Hepatitis B Vaccine: The Importance of the Birth Dose

  1. 2 of my children were born at home so didn’t get the vaccine until they were 2 and 4 years old. Do you think they should be checked for a chronic infection?

    • If any of their household contacts or playmates were chronic HepB carriers, getting them checked would be a very good idea. But this is something to discuss with your children’s pediatrician. Their status could be determined by a blood test, and a pediatrician could help you figure out if performing this test would be beneficial overall, given how at risk your children were.

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