By better understanding what worked in the past, we can better prepare for the future, says senior author Martin Cetron, M.D., director of the CDCs Division of Global Migration and Quarantine. Communities that were most successful during the 1918 pandemic quickly enacted a variety of measures. Those planning for the next pandemic need to carefully consider how to best use these strategies to protect people and decrease the potential impact of the next pandemic in their communities.
The 43 cities in the study were scattered from coast to coast and represented a combined population of approximately 23 million. In an exhaustive review of 1,144 primary and secondary sources that included U.S. census data, municipal records, newspapers and handbills covering a 24-week period Sept. 8, 1918 through Feb. 22, 1919 the researchers identified which NPIs were used in each city and when officials turned them on and off.
Using both actual death rates from pneumonia and influenza, and baseline rates for what would have been normal without a pandemic, the researchers found there were 115,340 excess pneumonia and influenza deaths attributable to the pandemic in these cities during the period studied. In comparing the death rates to when NPIs were turned on and off, they found that NPIs did mitigate the death rate, with a statistically significant association between increased duration of NPIs and reduced mortality.
Further, they discovered that city-to-city variation in mortality was associated with the timing, duration and combination of NPIs. St. Louis, Missouri, for example, closed schools and cancelled public gatherings relatively early in the pandemic and sustained these measures for about 10 weeks. The analysis shows that St. Louis had one of the largest drops in mortality while the NPIs were in force.