Public health officials and scientists studied the implementation of non-pharmaceutical interventions for epidemic mitigation in 43 cities in the United States from Sept. 8, 1918, through Feb. 22, 1919, when an influenza outbreak– one that killed 50 million people worldwide — became the last major pandemic to affect the United States. They did this to determine whether city-to-city variations in death rates were associated with the timing, duration and combination of non-pharmaceutical interventions. They concluded that they were.

The key, according to an article published in the Journal of the American Medical Association, is “early, sustained, and layered application of non-pharmaceutical interventions.” The doctors concluded that “such measures could potentially provide valuable time for production and distribution of pandemic-strain vaccine and antiviral medication. Optimally, appropriate implementation of non-pharmaceutical interventions would decrease the burden on health care services and critical infrastructure.”

The biggest misunderstanding about these interventions is they are an à la carte menu of options to be selectively implemented. This is dead wrong. They all must be implemented to achieve a layered effect.