Sometimes we take the benefits of modern medicine for granted, but a small dose of data and history can easily remedy that. The chart below, created by Valentine Svensson, a PhD student in molecular biology at Cambridge University, shows the dramatic decline in the incidence of measles in 20th century America.


You can see that the incidence of measles fell sharply after the vaccine was introduced in 1963, only 50 years ago. As the vaccine did its work, the incidence of measles dropped to zero by the end of the century. (The left-hand axis is graphed as a base 10 log, a common technique that statisticians use to bring in spread-out values and illuminate a trend.)

Lest we forget where we came from, here's a map that shows how deadly measles was in 1880. The map shows the ratio of deaths from measles to aggregate deaths, based on the tenth census ever conducted in this country. The graph at the lower left hand corner of the page shows how the states compared in terms of deaths by measles, while the key at the bottom right hand corner of the page tells you how many deaths the different shaded areas correspond to. (Click on the map, which is republished courtesy of the David Rumsey Historical Map Collection, to enlarge.)


In most states, fewer than 30 deaths per 1,000 were due to measles, or less than 3 percent of overall deaths. In some parts of Georgia, Nebraska, Colorado and Kansas, however, that proportion reached 3-6 percent of deaths, while in New Mexico it topped 6 percent of all deaths.

Finally, here's a graphic showing how measles spreads in an area without a vaccination program, by Bonnie Berkowitz and Lazaro Gamio of The Washington Post. The differently shaded squares represent four generations of infection, from Patient Zero (the darkest red square at the top left) to the people he or she infects (the next 17 reddish squares), the people they infect in turn (the next five lines of peach-colored squares), and the people they infect (the rest of the graphic). The dark squares represent the people who die from measles.


Without vaccinations, each measles case will infect 12 to 18 other people on average every 10 to 14 days. You can see how quickly the disease spreads from the first generation (Patient Zero) to 12 to 18 people in the second generation, 144-324 people in the third generation, and 1728-5832 people in the fourth generation. That adds up to more than 6,000 infections, all within 40 days. In a country with substandard healthcare and malnutrition, up to 28 percent of those infected will die.

Now contrast that with a country with full vaccination: In that scenario the disease would spread to 0.8 people every 10 to 14 days, and less than .3 percent will die. In a country like the United States, where most people have been vaccinated but pockets have not, the disease would spread to 1.1 to 2 people every 10-14 days and less than .3 percent would die.

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