April 15, 2020
The Centers for Disease Control and Prevention’s (CDC) Morbidity and Mortality Weekly Report released on Friday highlights geographic differences in COVID-19, with cases in all 50 states but not uniformly.
Cumulative incidence rates range from 20.6 in Minnesota to 915.3 in New York City per 100,000 residents as of April 7, according to the report. Increases in the incidence rate between March 31 and April 7 varied just as greatly: from 8.3 in Minnesota to 418 in New York City per 100,000 residents.
Illinois reported 47.0 cases per 100,000 people, with an increase in the incident rate of 106.3 per 100,000 people between March 31 and April 7.
Key jurisdiction-level data explain these vast ranges:
- The timing of COVID-19 introductions;
- Population density;
- Age distribution and prevalence of underlying medical conditions among COVID-19 patients;
- The timing and extent of community mitigation measures;
- Diagnostic testing capacity; and
- Public health reporting practices.
These factors are instrumental to gauging the effectiveness of community mitigation measures like social distancing and strategically allocating healthcare resources. The report also emphasizes that incomplete detection and delays in case reporting—which can also vary geographically—contribute to an under-reporting of COVID-19 cases.
The report shows how epidemiologic and population-level factors—like age distribution and underlying conditions—are critical for understanding community risk and future decision making during this pandemic.