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How to understand COVID-19 case counts, positivity rates, and other numbers

  • Comorbidity

    Comorbidity is an additional condition that contributes to a patient's death. In the case of COVID-19, some comorbidities, such as respiratory failure and sepsis, may be brought on by the coronavirus. Others, such as diabetes, hypertension, and Alzheimer's, may cause a patient's experience of the coronavirus to be more severe. While these conditions may play a role in worsening a patient's COVID-19 outcome, their deaths are still caused by the disease.

  • Demographic data

    Presenting demographic data for a disease means breaking down case and death numbers according to different characteristics of a population, such as age, gender, race, and ethnicity. Analyzing such data is important because it can reveal disparities in how a disease is impacting different groups of people. For example, the Kaiser Family Foundation's analysis has demonstrated that people of color in America have less access to COVID-19 tests, but are at higher risk for both contracting and dying from the disease.

  • Long-term care facility

    Nursing homes, assisted living facilities, and other forms of elder care are included in the blanket term long-term care facility. Such facilities have become a key area of study during the COVID-19 pandemic, as the disease has spread quickly through these homes for America's elderly population. As the COVID Tracking Project's Long-Term Care COVID Tracker reports: While residents in long-term care facilities make up less than 1% of America's population, they make up 42% of the country's COVID-19 deaths as of Sept. 10.

  • Looking at numbers in tandem

    One common mistake that one may make while looking at COVID-19 data is analyzing one metric in isolation. For example, one cannot make a case that a region is recovering from its COVID-19 outbreak by looking at a declining death rate. Death rates tend to lag case rates, as mentioned on a previous slide—a region's death rate may be decreasing while more people become infected, and the case rate climbs back up. Instead, you must look at how much testing your region is doing, how many cases are identified through that testing, how your healthcare system is faring, and the outcomes of recent cases in order to see a complete picture of the pandemic's current impact on your community.

  • Put numbers in terms of people

    COVID-19 numbers can often seem clinical when you're looking at a fancy dashboard full of color-coded charts and graphs. It can be challenging to remember that each value represents a person who has become sick or died from COVID-19. When reading a chart or a value in a news story, try to remember that the true units are American lives—and feel the urgency of reporting and understanding exactly what these numbers mean.

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  • Recognizing uncertainty

    All the COVID-19 numbers discussed in this story have some degree of uncertainty. Any given case count from a public health agency or other institution is likely missing people who were unable to get tested. Any test count might be combining values from different tests or conflating units. Any count of the lives lost may be missing many people who died due to the pandemic's impact but did not meet specific case definitions. And all this aside, many agencies have been figuring out how to report COVID-19 values as they do it, with new data reporting systems built and implemented along the way.

    We will likely not know the true scope of what the pandemic has cost America for many years to come. The numbers that you see now are simply the best attempts of the smartest people working on this topic to capture what statistics they can right now.

    [Pictured: Centers for Disease Control and Prevention (CDC) activated its Emergency Operations Center (EOC) to assist public health partners in responding to Covid-19.]

  • COVID Tracking Project

    The COVID Tracking Project at The Atlantic is one such attempt to capture what statistics are available. The Project, an effort comprised of journalists, scientists, public health experts, students, and other volunteers, collects data on COVID-19 cases, testing, and outcomes from state public health departments and synthesizes those data for the public. It has become a trusted source for testing data, used everywhere from ProPublica to the White House. The Project releases daily tweets on the current state of COVID-19 data, as well as regular blog posts on trends and data issues.

  • Johns Hopkins

    One of the first and most widely followed data trackers of the pandemic in the U.S. is managed by the Johns Hopkins University of Medicine. The tracker provides both global and U.S.-specific dashboards, which allow users to see case and death counts for regions as wide as the U.S. and as narrow as Los Angeles county. The Johns Hopkins tracker also provides resources on other aspects of the pandemic, such as testing and tracing, and articles that may help less scientifically minded readers understand the latest COVID-19 news.

    [Pictured: The COVID-19 global cases map by the Center for Systems Science and Engineering (CSSE) at Johns Hopkins University (JHU) seen displayed on April 29, 2020.]

  • Department of Health and Human Services

    The Department of Health and Human Services (HHS) is the federal government's primary source for COVID-19 data. You might not have heard of it before this pandemic, but it is actually an executive branch of the government which oversees the CDC, the National Institutes of Health (NIH), and other departments. The HHS has collected data on COVID-19 testing since U.S. testing began in February, and it has collected data on COVID-19 hospitalizations since it took over this collection from the CDC in July. Admiral Brett Giroir, the Assistant Secretary for Health under President Trump, currently serves as the country's COVID-19 testing czar.

    [Pictured: Health and Human Services Secretary Alex Azar speaks during a press conference on January 28, 2020 in Washington DC. With Secretary Alex Azar is (from left to right) Centers for Disease Control and Prevention Director Robert Redfield, National Center for Immunization and Respiratory Diseases Director Nancy Messonnier, and National Institute of Allergy and Infectious Diseases Director Anthony Fauci.]

  • State and county dashboards

    In many cases, the most reliable source for COVID-19 data is the most local source: your public health agency. You might look to the agency for your state, your county, or even your town to provide data and updates. Since these agencies have smaller spheres of people to monitor than federal public health departments, they can often quickly update values, notify their audiences when something goes wrong, and tailor their reports specifically for their communities. If you're not sure how to find your local agency, you might look to the COVID Tracking Project's sources, which list every state department.

    Such agencies are also great places to direct questions about what a certain data point means or where the numbers are coming from. In this time of great uncertainty and confusion, asking questions—no matter how dumb they may seem—is the best practice you can develop for understanding COVID-19 data.

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