Epidemic (Epi) Curves for Coronavirus COVID-19

William M. Detmer, MD, supported by the Unbound Medicine Team

Updated: Sunday, December 05, 2021 18:32 ET

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Cases and Deaths for Selected Countries

Daily Confirmed COVID-19 Cases in Selected Countries
COVID-19 Case Curves in 8 Selected Countries
Rolling 7-day average of confirmed COVID-19 Cases in selected countries. Note that the left axis is linear rather than logarithmic and represents therolling 7-day average of cases reported to the European CDC by each country. Horizontal axis represents days since confirmed case reached 30/day.
Data sources: Johns Hopkins University CSSE. Our World in Data.[1]
Countries with Highest COVID-19 Activity: New Cases
Countries with Highest COVID-19 Activity
Recent Confirmed Cases in countries with the highest reported COVID-19 activity (United States, Brazil, UK, Brazil, Russia, Spain, Germany, France, Italy, India, Turkey). Note that the left axis is linear rather than logarithmic and representsthe number of cases reported (rolling 7-day average) by each country.
Data sources: Johns Hopkins CSSE. Our World in Data.
Total Confirmed COVID-19 Deaths in Selected Countries
Total Confirmed Death COVID-19 in Selected Countries
Total number of deaths from COVID-19 in Brazil, China, India, Iran, Italy, Japan, Mexico, Russia, S. Korea, UK, and United States. Note that the left axis is linear rather than logarithmic and represents the cumulative number of deaths reported to the European CDC by each country. Horizontal axis represents days since the 5th total confirmed death.
Source: European CDC, Our World in Data.
U.S. Deaths by State and County: Percent Change in Last 7 days
Coronavirus COVID-19 Curves by State and County
Aggregate data from the Centers for Disease Control and Prevention (CDC) and state- and local-level public health agencies. County-level data is confirmed by referencing state and local agencies directly. Map shows percent change in deaths from previous7 days as of December 4, 2021.
Source: US Centers for Disease Control.
U.S. COVID-19 Cases by Race/Ethnicity
U.S. COVID-19 Cases by Race/Ethnicity
COVID-19 Cases in the U.S. by Race/Ethnicity. Race/ethnicity data is available for only 48% of cases reported to CDC. According to the US Census Bureau Race/Ethnicity in the U.S. population is approximately: Hispanic or Latino (18%), Black (13%), Asian (6%), Native American (1.3%), two or more races (3%), White, not Hispanic or Latino (60%).
Source. U.S Centers for Disease Control[2]

Projected Deaths from COVID-19 in the U.S.

Projected Deaths in the U.S. from COVID-19: November 29, 2021
Projected Deaths in the U.S. from COVID-19
Projected deaths from COVID-19 in the United States. Left: Cumulative reported COVID-19 deaths since February and forecasted deaths for the next four weeks in the United States. Models make various assumptions about the levels of social distancing and other interventions, which may not reflect recent changes in behavior. Right: “Ensemble” forecasts summarize the information from the individual forecasts.
The national ensemble forecast predicts that weekly reports of new COVID-19 deaths will be 6,200 to 11,400 and total between 805,000 to 817,000 by December 25, 2021.[3]
Sources: Institute for Health Metrics and Evaluation (IHME), an independent global health research center at the University of Washington,[4] Laboratory for the Modeling of Biological + Socio-technical Systems (MOBS), Columbia University (CU), Imperial College, London (Imperial), University of Geneva (Geneva), and University of Texas, Austin (UT). For other models see [3].

Global Epidemic Curve for COVID-19

Global COVID-19 Epidemic Curve - Cases & Deaths (WHO)
Global Epi Curve for COVID-19 (WHO)
Epidemic curve of confirmed COVID-19 cases by WHO Region and total deaths. Graph shows cases and deaths by weeek of case reporting through November 30, 2021.
Source: Coronavirus disease (COVID-2019) situation reports. World Health Organization.[5]
World Health Organization Regions
WHO Regions
WHO Member States are grouped into six regions. Each region has a regional office. The map shows the WHO regions and the location of the regional offices.

What is an Epidemic (Epi) Curve?

  • An epidemic curve, also known as an epi curve or epidemiological curve, is a statistical chart used to visualize the onset and progression of a disease outbreak.[6]
  • Epi curves typically display a graph of the onset of illness among cases in an outbreak.
    • Horizontal x-axis shows the date of illness onset among cases.
    • Vertical y-axis shows the number of cases.
  • For the COVID-19 outbreak, major agencies display cases differently:
    • World Health Organization (WHO) – show graphs based on the date of case reporting.[5]
    • US Centers for Disease Control (CDC) display cases by onset of illness. For COVID-19 the CDC has also started to report cumulative cases based on date of reporting.[2]

Flattening the COVID-19 Epidemic Curve

Flattening the COVID-19 Epidemic Curve
Flattening the COVID-19 Epidemic Curve
See below for explanation.
Source: US Centers for Disease Control (CDC), adapted by Unbound Medicine.
  • Without speedy and coordinated public health actions such as rapid testing, isolation of cases, "social distancing" and stay-at -home policies, the number of COVID-19 cases could rise beyond the capacity of the healthcare system to handle severe cases (see red curve in relation to healthcare system capacity line in figure above). This occurred in Wuhan, China and is happening now in parts of Italy.
  • The goal is to "flatten" the curve (green curve above) – reduce the daily rate of new cases so that the number of severe cases can be handled effectively by the healthcare system.
  • Note that public health actions taken to "flatten the curve" do not guarantee the reduction in total number of cases during a pandemic. That will be determined by additional factors such the speed by which other effective prevention measures (e.g., vaccines) are developed.

Infographics

Infographic | Flattening the Epidemic Curve
Flattening the COVID-19 Epidemic Epi Curve Infographic
Slowing the spread of the virus can reduce the chance of infection among high-risk populations and reduce the acute burden on healthcare systems and workers.
Sources: Community Mitigation Guidelines to Prevent Pandemic Influenza.[7] WHO Situation Reports.[5]
Infographic: Unbound Medicine

Tutorials

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References

  1. Total confirmed cases of COVID-19. Our World in Data. [https://ourworldindata.org/grapher/covid-confirmed-cases-since-100th-case]
  2. Coronavirus Disease 2019 (COVID-19) in the U.S. United States Centers for Disease Control and Prevention. [https://www.cdc.gov/coronavirus/2019-ncov/cases-in-us.html]
  3. COVID-19 Forecasts. U.S. Centers for Disease Control and Prevention. [https://www.cdc.gov/coronavirus/2019-ncov/covid-data/forecasting-us.html]
  4. United States COVID-19 Hospital Needs and Death Projections. Institute for Health Metrics and Evaluation (IHME), University of Washington, Seattle. 2020. [https://covid19.healthdata.org/projections]
  5. Coronavirus Disease 2019 (COVID-19) Situation Reports. World Health Organization. [https://www.who.int/emergencies/diseases/novel-coronavirus-2019/situation-...]
  6. Interpretation of Epidemic (Epi) Curves during Ongoing Outbreak Investigations. US Centers for Disease Control and Prevention. [https://www.cdc.gov/foodsafety/outbreaks/investigating-outbreaks/epi-curve...]
  7. Qualls N, Levitt A, Kanade N, et al. Community Mitigation Guidelines to Prevent Pandemic Influenza - United States, 2017. MMWR Recomm Rep. 2017;66(1):1-34.  [PMID:28426646]
  8. Coronavirus Locations: COVID-19 Map by County and State. USAFacts.org. [https://usafacts.org/visualizations/coronavirus-covid-19-spread-map/]

  9. Key Metrics for COVID Suppression. Harvard Global Health Institute. [https://globalepidemics.org/key-metrics-for-covid-suppression/]

  10. Nationwide COVID-19 Metrics Since April 1. The COVID Tracking Project. [https://covidtracking.com/data/charts/us-all-key-metrics]
  11. Quick-Learn Lesson: Create an Epi Curve. US Centers for Disease Control and Prevention. [https://www.cdc.gov/training/quicklearns/createepi/]
Last updated: December 5, 2021