When new families come to my practice, many parents are confused about why the hepatitis B vaccine is on the schedule for newborns. After all, hepatitis B is sexually and IV drug transmitted, right? And their baby isn’t into IV drug use and isn’t having sex. Why would their baby need a hepatitis B vaccine? Why does any baby need a hepatitis B vaccine? Who are these scandalous infants roaming the streets doing risky things?
Hepatitis B is a virus that affects the liver. If someone gets hepatitis B, there are a couple ways it can go. They can get sick, and then get better, and clear the infection, or it can become chronic, and be with them perpetually. Adults typically clear it, and babies and kids typically don’t.
When someone has chronic hepatitis B, they are at significantly higher risk of liver failure and liver cancer. Worldwide, it’s estimated that 350 million people have chronic hepatitis B, and more than 780,000 people die every year due to complications of hepatitis B (1). Hepatitis B is thought to be the cause of 50-80% of all liver cancer. The hepatitis B vaccine was actually our first vaccine for preventing cancer!
When we think about who in the world is walking around with chronic hepatitis B (remember, that’s 350 million people), we realize that most of them got hepatitis B when they were kids (2).
The younger a child is under 5 when they get hepatitis B, the more likely they are to develop chronic hepatitis B. In people older than five, fewer than 5% develop chronic hepatitis B. In kids under five, but older than one, it’s around 30%. But babies under age one – 90% of them develop chronic hepatitis B. Ninety percent!
How would a baby get hepatitis B, anyway?
Hepatitis B is a tenacious virus. It can survive, dried out, on a surface, for a week or more. It’s also very likely to actually infect someone if they’re exposed – up to 30% of people who encounter hepatitis B actually get the disease, as opposed to another famous virus, HIV, where the number is only 0.03% (4). There are many documented cases of people getting hepatitis B in bizarre circumstances – parents from their adopted children, people using the same blood sugar meter even though they were each using a clean lancet (needle), or from a shared surgeon or barber (5).
The first opportunity a baby has to contract hepatitis B is from their mom (or whomever is doing the gestating). Unlike some other viruses that can be transmitted through the placenta, this one typically needs some kind of blood exposure, whether that’s by amniocentesis or the actual process of being born.
Babies born to moms positive for hepatitis B should receive the hepatitis B vaccine and hepatitis B immunoglobulin (HBIG, premade antibodies to help fight it off). The combination is very effective for preventing the baby from getting hepatitis B.
All pregnant people should be screened for hepatitis B, but sometimes the wrong test is ordered, sometimes the test is missed, sometimes the result is missed, or sometimes they are not properly routed to a perinatal hepatitis B program to provide the immunoglobulin to protect the baby. It’s estimated that up to half of all hepatitis B-positive pregnancies are missed (6). Sometimes people become infected with hepatitis B after their initial prenatal screening, and so they don’t know that they have hepatitis B at the time of the baby’s birth. Though these babies really should get both HBIG and the vaccine, even getting just the vaccine helps prevent most infections. Vaccinating all babies helps fill in the gaps for potential missed maternal infections – it acts as a safety net.
The next opportunity to get hepatitis B is in the household. If someone has chronic hepatitis B, they can pass it along to the baby. While the virus is found in saliva, transmission is not very effective that way, although it can happen with pre-chewing a baby’s food, for example. But if there’s an accident, there’s blood around, and there’s some way to get into the baby’s circulation, then it can be transmitted. Around 40-60% of kids who grow up in hepatitis B-positive households will eventually become infected. To make things more complicated, many adults don’t actually know their hepatitis B status. Parents and grandparents from regions where hepatitis B is very common are much more likely to have hepatitis B, even without knowing it.
The next opportunity is in daycare, preschool, or wherever babies congregate. Though we’d all love our babies to be perfectly well behaved and speak or sign their intentions, the reality is, kids bite. Sometimes our kid is the bitee, sometimes the biter. Babies often have little inflamed spots in their mouths from teething, and biting and drawing blood, or in the infected kid breaking the other kid’s skin – these are all ways that hepatitis B can be transmitted.
The point is not that your kid will definitely encounter hepatitis B. The point is that if they do encounter hepatitis B in infancy or childhood, the consequences are much more serious than if they encountered it in adulthood. Becoming infected as a baby or kid means they’re significantly more likely to develop chronic hepatitis B, with the accompanying risk of liver cancer. And people with chronic hepatitis B can pass it on to others, perpetuating the problem. Not only that, but babies and kids don’t typically show symptoms when they contract hepatitis B. You wouldn’t necessarily know that they’d contracted the disease. That’s one of the reasons why we don’t always know where people are getting hepatitis B from – we might not know they have it until years later.
So how do you prevent that?
In the US we’ve tried various strategies to try to reduce the burden of hepatitis B. The first strategy was to test the high risk folks in pregnancy. As it turns out, nobody is great at identifying who is high risk. There are many risk factors, and most OBs were only looking for two or three risk factors. People are not exactly raising their hands saying, test me, I’m high risk!
The next strategy that was tried in the US was to test everyone but only immunize the kids in high risk families. When families decide that their child doesn’t need the hepatitis B vaccine, this is basically the strategy they’re adopting. They’ve decided that, though there are kids out there who are high risk and should get vaccinated, that that doesn’t apply to their kid, that they are not high risk and that their kids don’t need the vaccine.
But this strategy has been tried, and it didn’t work. Between the years of 1981, when the first hepatitis B vaccine was licensed for use in the US, and 1991, when the first comprehensive strategy to eliminate hepatitis B advocated for the use of hepatitis B vaccine in all newborns, various strategies targeting high risk groups were tried. Though some of the high risk groups showed improvements, there was not much impact on the overall rates of hepatitis B.
What does work is immunizing all babies. This is the strategy that the WHO advocates. Since the US adopted this recommendation, reported cases of acute hepatitis B have been reduced by 94% in the cohorts that received the vaccines as babies and kids (6). Prevent acute hepatitis B and you’ll prevent chronic hepatitis B, especially in the age groups that are especially prone to developing chronic infections – babies and kids. Prevent chronic hepatitis B, and you prevent a lot of liver failure, liver cancer, and lost years.
Is the vaccine safe?
Hepatitis B vaccine is what I call a low drama vaccine. Rarely are there fevers or other problems. It hurts a little going in, but that’s it. It’s an elegant vaccine that even newborns can receive, without having to wait 6 weeks like many other vaccines. All babies who are 2000 grams or more (roughly greater than 4.5 pounds) can get the vaccine and respond appropriately, developing immunity to hepatitis B that is thought to last 20+ years, possibly lifelong. Certainly it protects them during the years when infection is most likely to result in grave consequences.
So, that’s the whole story on hepatitis B vaccine. It’s not just for scandalous infants. It’s not just for other people’s babies. It’s to protect your baby at a time when it really matters. It’s to build a foundation of immunity that will serve your child for his entire life.
- WHO | Hepatitis B [Internet]. WHO. [cited 2016 Jun 1]. Available from: http://www.who.int/mediacentre/factsheets/fs204/en/
- WHO | Hepatitis B – Emergency Preparedness [Internet]. WHO. [cited 2016 Jun 1]. Available from: http://www.who.int/csr/disease/hepatitis/whocdscsrlyo20022/en/index1.html
- Pinkbook | Hepatitis B | Epidemiology of Vaccine Preventable Diseases | CDC [Internet]. [cited 2016 Jun 1]. Available from: http://www.cdc.gov/vaccines/pubs/pinkbook/hepb.html#prevention
- CDC – Bloodborne Pathogens – Occupational Exposure FAQs – Infection Control in Dental Settings – Oral Health [Internet]. 2013 [cited 2016 Jun 1]. Available from: http://www.cdc.gov/oralhealth/infectioncontrol/faq/bloodborne_exposures.htm
- Immunization Action Coalition. Unusual Cases of Hepatitis B Transmission (PDF).
- CDC. A Comprehensive Immunization Strategy to Eliminate Transmission of Hepatitis B Virus Infection in the United States. MMWR. 2005 Dec 23;54(RR16):1–23.