Randomized and Placebo Control Approach in Light of The Biggest Public Health Experiments Ever: The 1954 Field Trial of the Salk Poliomyelitis Vaccine

One of the largest and most expensive medical experiments was to assess the effectiveness of?Salk Poliomyelitis Vaccine carried over a million young children. The study was most prominent for the use of randomization and placebo controls in the history of statistics and medical science.

Some statistical approaches to determine efficacy of vaccine:

• Vital Statistics Approach: The strategy involves distributing the vaccine widely and observing its impact on infection rates in subsequent seasons. However, there are challenges with this approach as the incidence of polio varies from season to season, and the disease's symptoms can be difficult to differentiate from those of other illnesses, leading to subjective diagnoses by physicians.
• Observed Control Approach: The approach involves vaccinating one group and introducing a similar control group without the vaccine. However, it also faces challenges such as the potential bias of physicians' diagnoses towards the vaccinated or control groups, and the fact that volunteers for vaccination are often more educated and better off than non-participants.
• Randomized and Placebo Control Approach: In case of placebo-controlled approach a group inoculated with a placebo material that looked exactly like a vaccine, but without antigenic power?so that the controls might be inoculated and otherwise treated in just the same fashion as were the vaccinated. The experiment was designed in a double-blind format in which both the subject getting the treatment and the diagnosticians who will evaluate the outcome were unaware of the treatment given. To ensure an equal chance of receiving the vaccine or placebo, subjects are assigned randomly through a careful randomization procedure, such as flipping a coin. The rate of infection in the vaccinated group is seen to be half that in the control group.

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