Vaccines: An Historical Perspective
Back when our nation was in its infancy, the Continental Army had attacked the British at Quebec. Things did not go well for our army in 1776. The problem was not the British troops, as much as it was an outbreak of smallpox afflicting approximately 5,000 Continental Army soldiers, half of the entire force. A hasty retreat was ordered. The following year, George Washington ordered smallpox inoculation for every soldier who did not have evidence of prior infection. Variolation, the procedure at the time, was rather crude and involved inoculating an individual with infectious material from another person with smallpox. Variolation had a 1 percent likelihood of fatality, whereas smallpox carried a 30 percent risk of fatality. The math worked.
In 1796, Edward Jenner, an English physician, had a better idea. He recognized that dairymaids rarely contracted smallpox, even though most of them had been infected with cowpox. Jenner decided to inoculate the 9-year-old son of his gardener with material from a cowpox lesion from a milkmaid named Sarah Nelmes. The child research subject was subsequently exposed to smallpox and did not contract the disease. Jenner then vaccinated other children, including his own son. He published his results in 1798, and the practice spread. The vaccine was upgraded in the 1800s to contain vaccinia instead of the cowpox virus.
Up until 1966, smallpox outbreaks were occurring in Africa, Asia, and South America. An intensive eradication program backed by the WHO began in 1967. In 1975, a three-year-old girl had the last case of naturally acquired smallpox. In 1980, the disease was declared eradicated. At the present time, smallpox remains the only disease affecting humans that has been eradicated. Other infectious diseases have been controlled, but not yet eradicated, largely through the use of vaccination.
The 20th century saw the development of multiple vaccines. Tetanus vaccine, developed in 1924, proved to be quite effective in preventing tetanus infection in contaminated battlefield wounds in WW II. Only 12 US servicemen acquired tetanus during that conflict and half of that number had never received a single dose of the vaccine. Other vaccines followed, including polio and measles vaccines. Again, the incidence of the targeted diseases declined dramatically, until recently, that is.
Over the past few years, the incidence of measles in particular has been on the rise, not just in the United States, but in European countries, as well. The United Kingdom recently lost its “measles free” status. There was an outbreak at Disneyland four years ago. Total cases of measles in the United States, so far, number more than 1200 with 30 states reporting outbreaks.
What is happening? Isn’t the vaccine effective? The vaccine remains effective, but only if people receive it. When vaccination rates drop below 95 percent, the disease has the opportunity to gain a foothold and spread. Declining vaccination rates, coupled with the ability of people to travel easily from one continent to another, have contributed to the resurgence. Perhaps, if more individuals embrace vaccination, we can resume progress towards eradicating this sometimes fatal disease, as well as others.
Stephen Mange, M.D.
Stephen Mange is a pediatrician, recently retired after over 35 years at the Davidson Clinic. He and his wife, Pamela, are the parents of three grown daughters and two granddaughters.