given the rising number of measles cases, being up to date with your immunizations ( it takes two doses for measles ) is very important.
but the reality is that hepatitis b is a disease that affects many infants and young children worldwide. and unfortunately, the younger you get the virus, the more likely it is to become a chronic infection that can cause cirrhosis or liver cancer. while most diseases are more severe if you get them as an adult, hepatitis b is paradoxically worse if you get it young. infants less than one year old who get hepatitis b have an 80-90 per cent chance of developing a chronic infection , compared to 30-50 per cent of children under 6 and less than 5 per cent of adults.
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between 1990 (about the time when universal hepatitis b vaccinations started) and 2006, the rate of hepatitis b infection fell by 81 per cent to the lowest level ever recorded, and the decline was greatest among children. today, most hepatitis b infections in north america occur in adults. but worldwide, in places where hepatitis b is still common, infections can and do occur very frequently in children.
which raises the question of how children and infants can be infected if hepatitis b is spread through sex and dirty needles. here, too, we have forgotten our history. although less frequently seen in north american now, worldwide one of the most common methods of hepatitis b spread is from pregnant mothers to their babies at the time of birth. also, while hepatitis b is an infection that lives in bodily fluids, it can survive outside the human body for several days, which means that sharing contaminated household products is a possible source of infection.
in the end, there is a very simple answer to the question of why we vaccinate babies against hepatitis b. universal vaccination programs against hepatitis b have resulted in drastic reductions in hepatitis b cases in north america. unfortunately, in the rest of the world, where resources are scare and vaccines are not widely available, hepatitis b remains a huge problem .
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christopher labos is a montreal doctor and an associate with the mcgill office for science and society. he also co-hosts a podcast called the body of evidence.