For ages I’ve wanted to write a post about science and epidemiology of vaccines, the illnesses they prevent, and the adverse reactions that can occur because of them. I am gathering information to finally do this, but it is going to take a lot of time. I’ve spent several hours yesterday and today wading through literature just on one vaccine – Hep B. I think I’m going to do this piecemeal, and then hopefully do a wrap up when it’s all said and done; otherwise, between my actual paying job and my family, it’s never going to happen. I could write books on each of them – people have written books.
My goal here is to try to put the risks of vaccination into perspective with the risks of choosing not to vaccinate. My general disclaimer stands – while I am a scientist, I am not a medical doctor. I am also not an epidemiologist, or a public health professional, or a statistician. I do my best to provide source material for the numbers I give and the statements I make, and if you want me to explain something more, just ask. I am focusing my discussion primarily on incidence data from the U.S.; this is partially because it’s easier for me, and partially because it’s more relevant to the rampant fear of vaccines in this country. My personal stance on vaccines is not the point of this, but you can read more about that here, if you want.
HepB – The Hepatitis B Vaccine
HepB is a three dose series, given at birth, 1-2 months, and 6-18 months (source: CDC vaccine schedule). It reduces the transmission of hepatitis B, a virus transmitted primarily by contact with infected blood and bodily fluids.
In my personal discussions with pregnant moms, I heard a lot of skepticism as to why HepB is routinely administered to all infants, when hepatitis B infection occurs primarily in certain high risk segments of the population – people who have unprotected sex, IV drug users, etc. A lot of people said, well, that’s not me and it’s unlikely to be my child, so why should I put my newborn at risk of an adverse reaction to the vaccine?
Ok, so that’s the rub: the HepB vaccine is incredibly safe. The primary adverse reaction is anaphylaxis (severe allergic reaction to the vaccine), which occurs in an estimated 1 in 1.1 million doses. Anaphylaxis is serious, but treatable – and because the vaccine is administered in a medical setting, the risks are even lower. No deaths have occurred because of the HepB vaccine, in the U.S. or elsewhere. HepB is part of a routine schedule of vaccinations in 179 countries – a LOT of people have been vaccinated (source)!
So what about deaths and adverse outcomes from hepatitis B? Yeah – a LOT. Before the vaccine was introduced in the mid 1980s, annual new hepatitis B infections were increasing rapidly, peaking at 26,654 new cases in 1986 (source). It is estimated that 700,000 – 1,400,000 people are currently infected with the hepatitis B virus, most of whom do not know they are infected (source). Now that HepB vaccine is administered to most newborns and young children, the rate of new infections has dropped dramatically, to 3350 cases in 2010 (source). The number of people in the U.S. who die each year because of hepatitis B infection (as in, the official cause of death) is hovering around 1700 for the last few years (source).
Most of the deaths from hepatitis B are in older people – that is, not infants dying of acute infections. Hepatitis B can cause a serious acute infection, or a chronic illness. The chronic infection and resulting liver inflammation can lead to cirrhosis and cancer – hepatitis B is one of the leading causes of primary liver cancer. So, when an infant is vaccinated, it reduces the transmission from mother to infant, as well as reducing the rates of subsequent infection later in the child’s life. As more generations of infants and children are vaccinated with HepB, the rates of hepatitis B incidence and related deaths will continue to drop.
To sum up, hepatitis B kills thousands of people every year, while the vaccine kills ZERO. Hmm.
