Mortality in Puerto Rico after Hurricane María (NEJM Study)

Published in the New England Journal of Medicine on May 29, 2018, this landmark study by researchers from Harvard T.H. Chan School of Public Health, the University of Colorado, and Carlos Albizu University estimated that 4,645 excess deaths occurred in Puerto Rico in the 102 days following Hurricane María — a figure 70 times higher than the official government count of 64.

The study used a household survey of 3,299 randomly selected households across Puerto Rico to estimate excess mortality. Key findings included:

• An estimated 4,645 excess deaths (95% confidence interval: 793 to 8,498)
• One-third of post-hurricane deaths were attributed to delayed or interrupted medical care
• The mortality rate for the period was 14.3 deaths per 1,000 people (compared to 2017 baseline of 9.5)
• Communities in lower socioeconomic terciles had the highest rates of disrupted medical services
• 83.2% of households experienced prolonged interruption of cellular phone services
• 57.6% experienced interruption of water services

The study exposed the catastrophic failure of the U.S. government's disaster response and forced the Puerto Rican government to commission its own review, which ultimately revised the official death toll to 2,975. However, many researchers believe even this figure is an undercount.