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Newborn Babies Don’t Have Sex, So Why Do We Vaccinate Them for a Sexually Transmitted Disease?

SkepDoc's Corner

Harriet Hall

February 17, 2016

Vaccination is arguably the greatest accomplishment of modern medicine; vaccines have saved millions from death and disability, and smallpox has been eradicated forever. But vaccines are not without their critics. Since Jenner first experimented with cowpox, there have been people who have rejected vaccinations for various reasons, usually appallingly wrong-headed ones.

A strong anti-vaccine movement continues to thrive today. Some people reject all vaccines for religious or ideological reasons; some complain (against all evidence) that we give “too many too soon”; some have specific objections to specific vaccines. Every objection the anti-vaxxers have come up with has been soundly debunked, but not everyone has heard the debunking or accepted it.

Hepatitis B Virus

Perhaps the hardest vaccine to explain is the hepatitis B vaccine that is routinely given to newborns within twenty-four hours of birth (followed by two more doses one and six months later). Hepatitis B is a sexually transmitted disease. A newborn can’t even climb into the next crib, much less fornicate with its occupant. Newborn babies don’t have sex, and they’re not likely to have sex for many years to come. So at first glance it seems positively idiotic to vaccinate them at birth. It may seem only logical to assume it must be some nefarious conspiracy to enrich doctors and vaccine manufacturers. You could stop there and condemn the practice, or you could wait to hear what Paul Harvey called “the rest of the story.”

Hepatitis B is sexually transmitted through vaginal, anal, or oral sex. It can also be transmitted by shared needles: drug injection, body piercing, or tattooing. It can be directly transmitted to a newborn by an infected mother. And it can be transmitted by personal items contaminated with blood or bodily fluids (razors, toothbrushes, nail clippers, etc.).

OK, so babies don’t have sex, abuse drugs, or share razors. And mothers can be tested for the virus; if they don’t have it, there is no risk of them transmitting it to their babies. So are there any valid reasons to vaccinate newborns?

Yes, there are very compelling reasons. For one thing, testing mothers is not foolproof. False negative test results are possible. But the most likely source of hepatitis B infection for children is not their mother, but the other children and adults they will encounter as they grow up—any of whom might be infected without knowing it. Children learn to share in preschool. They share their toys; they share their colds; and they share their bodily fluids. The hepatitis B virus can survive outside the body for seven days. Theoretically, an infected person could inadvertently contaminate a doorknob or a toy with saliva, and a child could touch the object and transfer the virus into his own body by touching a skin lesion or putting his fingers in his mouth. Exposure doesn’t have to be by direct injection or through breaks in the skin; mucosal exposure is enough.

The disease itself is subclinical (no symptoms) in up to 70 percent of cases. In children and immunocompromised adults it is typically asymptomatic. In 30–50 percent of adults it causes an acute illness with jaundice, fatigue, nausea, vomiting, and abdominal pain, lasting several weeks. There is no specific treatment for the disease. Most healthy adults who become infected will recover completely with no lasting consequences, but a few will die from acute liver failure. Up to 5 percent of infected adults will develop chronic infection. And 20–30 percent of those who are chronically infected will develop cirrhosis and/or liver cancer, and many of them will die. The World Health Organization (WHO) estimates that more than 780,000 people die every year due to complications of hepatitis B infection.

Here’s the really bad news: chronic infection is far more likely to develop in children than in adults. A whopping 80–90 percent of children infected before the age of one, and 30–50 percent of those infected before the age of six, will develop a chronic infection. This puts them at risk of liver failure and liver cancer later in life.

The complete series of three doses of vaccine is more than 95 percent effective in preventing infection; the protection lasts at least twenty years and is probably lifelong. Over a billion doses of vaccine have been given, so we can be reassured that it has an excellent safety record. It causes only mild problems: soreness at the injection site in 25 percent and a transient fever in 7 percent of recipients. There is a less than one in a million risk of a serious allergic reaction, and no other serious adverse effects have been reported. The World Health Organization strongly recommends it be given at birth, and 183 of its member states currently vaccinate infants. Vaccination has reduced the rate of chronic infection in children in some countries from 15 percent to less than 1 percent. Since Taiwan introduced universal vaccination, the incidence of liver cancer in children has dropped dramatically, as have deaths from liver cancer.

Now that you’ve heard “the rest of the story,” I think it will be obvious to you why we give newborns the hepatitis B vaccine. Newborns don’t have sex, but they are uniquely vulnerable to a preventable disease that can cause liver failure and cancer. The younger the child, the more vulnerable; the earlier the vaccine is given, the better they are protected. It has been proven effective and safe, and doctors and scientists around the world agree that giving it on the first day of life is the best insurance against future illness and death from liver cancer. Now that you understand why they recommend it, maybe you can explain to your vaccine-wary friends that however silly it may seem, giving a vaccine for an STD at birth really is the right thing to do.

Think about it: we have a vaccine that can prevent cancer! (Actually we have two; the other is the HPV vaccine.) It would be a real shame to deny that protection to a child because of misunderstandings, misinformation, ideology, or fear-mongering.

For further information, see the WHO website and the CDC website.

Harriet Hall

Harriet Hall's photo

Harriet Hall, MD, a retired Air Force physician and flight surgeon, writes and educates about pseudoscientific and so-called alternative medicine. She is a contributing editor and frequent contributor to the Skeptical Inquirer and contributes to the blog Science-Based Medicine. She is author of Women Aren’t Supposed to Fly: Memoirs of a Female Flight Surgeon and coauthor of the 2012 textbook Consumer Health: A Guide to Intelligent Decisions.