Pediatricians Offer a Primer on Hepatitis B, Explain Why We Should Vaccinate Infants
Dr. Pia Fenimore
Dr. Joan Thode
Ever notice how people prepare based on what they have witnessed? Consider car mechanics who never miss an oil change and stay on top of routine vehicle maintenance because they see firsthand the consequences of what happens when they don’t.
In the same way, doctors have in-depth knowledge of how the body works at a cellular level, along with a deep understanding of how specific diseases damage those cells and affect their patients’ quality of life. We use our knowledge to support vaccination in the same way that car mechanics use their expertise to guide their actions.
And while we can’t take you to medical school, we can offer a pertinent crash course to help you understand the cells and organs of the body, how they function and what happens when specific diseases disrupt their processes. Our goal is to empower you with knowledge, so you feel confident in your decisions about the vaccines recently brought into an uncertain light by the U.S. Department of Health and Human Services.
Today’s topic is hepatitis B, and so we begin with the organ it affects: the liver.
Body’s ultimate multitasker
Scientists have identified more than 500 functions the liver conducts for the body, and its molecular processes impact every other organ system. Blood filters through the liver on its way back to the heart, and the blood from intestines, filled with absorbed nutrients and other ingested compounds, goes directly to the liver. At any given time, the liver is processing around 13% of your total blood volume.
And “process” blood it does: Each liver cell (called a hepatocyte) can perform a wide range of tasks using highly specialized cellular “machinery,” making these cells some of the most sophisticated in our entire body.
As blood filters sequentially through the connected groups of hepatocytes, their work falls into several key categories: storing compounds needed for normal body function; producing essential compounds; converting compounds at a molecular level; removing waste, toxins and excess compounds that could be harmful; and monitoring the blood for infection. We will return to these critical functions in a bit.
When infection occurs
When the hepatitis B virus travels through the bloodstream to the hepatocytes, it attaches to a receptor on the cell surface and is brought inside. Once inside, the virus travels to the core of the cell, called the nucleus, and establishes its DNA there. The additional hepatitis B DNA starts using the liver cell’s machinery to create specific proteins the cell would not have made on its own. These proteins interfere with the liver cell’s normal functions. A hepatitis B-infected hepatocyte loses function and enters a stress state, known as oxidative stress, as it struggles to compensate for the destructive new tenant.
For patients with hepatitis B infection, the disruption of hepatocyte function affects their entire bodies.
Now, let’s return to the categories of function we named earlier. Without normal storage of iron, glycogen or vitamins, the patient becomes anemic, energy-deficient and weak. The inability to produce clotting factors and other essential proteins leads to easy bleeding, while impaired fluid balance results in swelling. Weakened inflammatory immune responses allow for severe infection, and decreased protein production causes hindered growth, hormone imbalances and a reduced ability to circulate vitamins in the bloodstream. Impaired cell function leads to ineffective absorption of medications, as well as abnormal cholesterol levels, reduced bone health and fatigue. And when waste removal falters, proteins and toxins accumulate in the bloodstream, negatively affecting multiple organs, including the brain.
While our immune system does try to combat hepatitis B virus, the virus enters liver cells so quickly and hides so deeply within the nucleus of the cell that the immune system ultimately resorts to attacking the liver cells themselves.
Another word for an immune system attack on cells is inflammation.
Hepatocytes are therefore dealing with oxidative stress from within and inflammatory stress from the outside for extended periods of time. This persistent barrage starts to shut down and essentially scar the hepatocytes, leading to a condition called cirrhosis. This cellular change — along with the impaired cell function — is permanent. What logically follows is liver failure, which leads to the failure of myriad body systems and can ultimately cause death.
Prolonged oxidative stress also affects the hepatocyte’s DNA, causing damage that must be continually repaired. This damage often leads to genes that regulate cell growth and other key functions to inappropriately turn on or off, resulting in cellular dysregulation, which is known in medicine as cancer.
Hepatocellular carcinoma is the most common type of liver cancer (accounting for about 90% of cases), and 54% of all cases of this cancer are attributed directly to chronic hepatitis B infection.
All of this is why physicians have a deep respect for hepatitis B and a strong commitment to preventing this disease in our patients. We know the devastating consequences of disrupted liver function, and we never want our patients to suffer from something we can help prevent.
Why infants are at highest risk
We pediatricians understand how much more vulnerable infants’ hepatocytes are to viral invasion compared to those of adults. If adults are infected with acute hepatitis B, about 95% will maintain normal liver function. When children become infected, 30% will develop liver failure from cirrhosis, and if an infant is infected, that risk rises to 90%. Ninety percent of infants infected with hepatitis B will develop chronic hepatitis with all the complications we described above.
This is why pediatricians support the newborn dose of hepatitis B vaccine: We can’t guarantee that a newborn won’t be exposed during this highly vulnerable period by their mother or others around them. Unfortunately, maternal testing is not perfect. If a mother contracts hepatitis B during her pregnancy, there is a window of two and a half months after initial infection in which she could test negative on screening tests but still transmit hepatitis B to her baby.
And other adults in the newborn’s circle of family and friends may be among the millions of Americans unknowingly infected, as the infection is often clinically silent in adults. National data indicates that 2.4 million U.S. adult are chronically infected by hepatitis B.
Because hepatitis B can also be transmitted through “mucosal membranes,” including the moist inner surfaces of the mouth and nose, well-meaning, affectionate family members can unknowingly pass the virus to a vulnerable baby simply through routine interactions. (Who can resist smooching a newborn?)
Moreover, babies often put anything they can grab into their mouths. Hepatitis B can live on surfaces for a week, and once inside the body, it’s aggressive — 50 to 100 times more infectious than HIV.
Vaccination is our best defense against hepatitis B infection in our children.
Does the vaccine work?
History proves that the vaccine works.
In 1981, the hepatitis B vaccine was tested for safety and approved for use, but at first was only given to babies of hepatitis B-infected mothers or to “high-risk” populations. Unfortunately, this limited approach did not significantly reduce childhood hepatitis infections over the following decade.
Research showed that of the 30,000 children with hepatitis B in 1991, only half were infected by their mothers; the other half acquired it from other sources. Once the recommendation shifted to protect all newborns with a dose of the vaccine, cases of infant and childhood hepatitis B dropped dramatically. To nearly zero.
With the drop in childhood hepatitis B cases, we also (logically!) saw the decline in childhood cirrhosis and later liver cancer cases.
Is the vaccine safe?
Yes! The vaccine is not a live virus and cannot cause hepatitis B infection. It contains only proteins made in a lab. These proteins are specific to hepatitis B so the immune system can learn to recognize them. This primes white blood cells to attack and neutralize real hepatitis B virus if exposure ever occurs.
We are equipping our newborns to fight a virus at a time when their immune system is too immature to defend them and their liver is most vulnerable to damage.
For that reason, the American Academy of Pediatrics continues to recommend giving newborns a dose of hepatitis B vaccine within 24 hours of birth, with additional doses at 1 to 2 months and 6 to 18 months.
By reminding the immune system with the additional doses, we exponentially increase the number of white blood defense cells primed to seek and destroy hepatitis B virus.
Millions of infants and children have safely received the hepatitis B vaccine. As with any vaccine, an appropriate immune response may include a low-grade fever afterward. The only significant, documented safety concern is an extremely rare risk of anaphylaxis, seen in about 1 in every 600,000 doses. Medical offices are well prepared to treat this rare event.
Pediatricians and the American Academy of Pediatrics fully endorse the original hepatitis B vaccination schedule that is based on science and designed to maximize prevention. For life.
The U.S. Department of Health and Human Services’ rationale for making the hepatitis B vaccine optional for infants is unclear, especially since the risk of hepatitis B has not decreased: 22,000 Americans become infected by hepatitis B each year. There are no specific “high-risk” groups among infants and children: They are all high-risk as they all have livers with no defense tactics against such an aggressive virus.
History demonstrates the vaccine’s effectiveness in keeping hepatitis B from stealing our kids’ happy and healthy childhoods and future potential.
We hope this article empowers you with the knowledge you need to make an informed decision for your own children.
Pia Fenimore, M.D., is a pediatrician at Lancaster Pediatric Associates and vice chair of pediatrics at Penn Medicine Lancaster General Health. Dr. Joan Thode, M.D., is a pediatrician at Penn Medicine Lancaster General Health Roseville Pediatrics. Both are fellows of the American Academy of Pediatrics.
