Results There were 115 340 excess pneumonia and influenza deaths (EDR, 500/100 000 population) in the 43 cities during the 24 weeks analyzed.
There was a statistically significant association between increased duration of nonpharmaceutical interventions and a reduced total mortality burden (Spearman r = −0.39, P = .005).
Optimally, appropriate implementation of nonpharmaceutical interventions would decrease the burden on health care services and critical infrastructure.
Of the 66 most populous cities, the remaining 23 had incomplete archival and mortality records.
The Weekly Health Index is the most complete extant compilation of weekly pneumonia and influenza mortality data in US urban areas during the 1918-1919 pandemic.
In 1920, these 43 cities had a combined population of approximately 23 million (22% of the total US population).
In the ANOVA model, each possible combination of nonpharmaceutical interventions was treated as an independent variable to test for layering effects. »
