It is recommended by the CDC (Centers for Disease Control) that everyone get a flu shot this year. Before we consider why, a look at the history of vaccines will be useful.

It is recommended by the CDC (Centers for Disease Control) that everyone get a flu shot this year. Before we consider why, a look at the history of vaccines will be useful.

Smallpox was a devastating disease for thousands of years, but in 1796 an English doctor named Edward Jenner observed that milk maids who had gotten cowpox seemed never to get smallpox. He developed a theory that if someone were to be intentionally infected with cowpox and then exposed to smallpox they would not come down with the dread disease. He tested his theory and in 1801 published, “On the Origin of the Vaccine Inoculation,” in which he summarized his discoveries and expressed hope that “the annihilation of the smallpox, the most dreadful scourge of the human species, must be the final result of this practice.”

In late 1975, Rahima Banu, a three-year-old girl from Bangladesh, was the last person in the world to have naturally acquired variola major (the worst strain of smallpox) and the last person in Asia to have active smallpox. She was isolated at home with house guards posted 24 hours a day until she was no longer infectious. A house-to-house vaccination campaign within a 1.5 mile radius of her home began immediately, and every house, public meeting area, school, and healer within 5 miles was visited by a member of the Smallpox Eradication Program team to ensure the illness did not spread. A reward was also offered to anyone for reporting a smallpox case. On May 8, 1980, almost two centuries after Jenner published his hope that vaccination could annihilate smallpox, the World Health Organization officially declared the world free of this disease. Since this is the only example of the complete elimination of a widespread deadly disease we can easily see why the eradication of smallpox is considered the biggest achievement in international public health.

There is much to be learned from this story. First, a highly effective intervention was developed (in 1796) long before there was any theoretical framework for how or why such an intervention might work. Second, it was not necessary to use the actual disease-causing agent to make an effective vaccine against it. Third, we now know that smallpox vaccine results in immunity in only 95 percent of cases, but it has been 100 percent effective in completely eliminating the disease from the face of the earth. Finally, and most importantly, the way that victory was finally achieved was by isolating cases and immunizing all possible contacts. This targeted immunization succeeded where previous efforts failed by ensuring it was unlikely that anyone not immune to the disease would come in contact with the virus. By creating this community immunity (also called herd immunity) the vaccine’s imperfect effectiveness was good enough to stop the spread of disease.

Do you remember mumps? Before the U.S. mumps vaccination program started in 1967, mumps was a universal disease of childhood. Since the pre-vaccine era, there has been a more than 99 percent decrease in mumps cases in the United States. It is therefore tempting to forego the pain and trouble of immunizations. But if a large percentage of the population does that, an isolated case of a traveler with mumps coming into the community can easily turn into a mumps outbreak as it jumps from one un-immunized person to another. If everyone in the community were vaccinated the chance of a sick person coming into contact with someone who is not immune would not be zero (because the vaccine is not 100% effective), but it would be much lower. Mumps is included in the MMR that is universally recommended at 12-15 months and 4-6 years of age. According to the CDC Two doses of the vaccine are 88 percent effective at protecting against mumps. The effectiveness of most vaccines rests in large part on community immunity. Next week we will consider the flu vaccine.

The Health and Wellness Coalition of Runnels County is comprised of health care professionals throughout the county. Members meet on the first Thursday of the first full week of the month.