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

  • Test wait time

    A test wait time, somewhat intuitively, refers to the length of time you wait between getting tested for COVID-19 and receiving your results. Ideally, test wait times should be two to three days if not shorter, allowing people who have been tested to act quickly to protect themselves and others while they are still symptomatic. Some potential COVID-19 patients have had to wait much longer this summer, however, due to lack of adequate testing supplies in states like Arizona and Texas. Reports on test wait times tend to be anecdotal; federal public health agencies and most states do not publish these numbers.

  • Current hospitalizations

    Hospitalizations have become a useful metric for tracking COVID-19's impact on different regions and healthcare systems. The figure refers to the number of patients who are currently hospitalized due to severe cases of COVID-19. These patient counts may include only patients with confirmed cases of COVID-19 (identified through PCR testing), or they may include both confirmed and probable or suspected cases, depending on who is reporting the numbers.

  • Cumulative hospitalizations

    A cumulative hospitalizations figure refers to the total number of people in a population who have been hospitalized due to severe cases of COVID-19. Similar to cumulative case counts, these figures are often not useful for tracking the pandemic's impact over time but can be used to identify demographic trends. For example, the CDC reports that Black Americans are 4.7 times more likely to be hospitalized for COVID-19 compared to white Americans, as of Aug. 18.

  • Hospital capacity

    Keeping track of current hospitalizations for a given region, such as a state or county, allows researchers and public health leaders to calculate that region's hospital capacity: the share of available hospital beds which are currently occupied. The Department of Health and Human Services (HHS) reports hospital capacity estimates for every state, including the percent of all beds occupied (not COVID-specific), the percent of beds occupied by COVID-19 patients, and the percent of ICU beds occupied. These figures faced a great deal of public scrutiny after the HHS took over hospital data collection and reporting from the CDC.

  • Outcomes

    Outcomes refer to the potential results of the disease. For COVID-19, these typically include death or recovery. COVID-19 patients who have underlying conditions such as diabetes and chronic kidney disease have an increased risk of more severe disease outcomes, meaning that their chances of hospitalization and death may be greater.

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  • Recovered

    When an individual infected with COVID-19 is included in a recovered count, it means that they are no longer considered to have symptoms or be in danger of spreading the virus to others. Many public health agencies report recovered figures, but definitions for how the figures are determined vary greatly; recovered cases may include specifically patients discharged from the hospital or include all COVID-19 cases that are no longer active. As a result, it's generally not possible to compare these numbers from state to state or across other jurisdictions.

  • COVID-19 death

    The death toll of a disease is the ultimate way to track its impact on a population. However, more than any other metric, COVID-19 death tolls lag behind outbreaks in showing how badly a particular region has been hit, meaning that this number rises much later than others, such as cases and hospitalizations, as the disease progresses in vulnerable patients and these numbers are tallied. As a result, epidemiologists recommend watching case and hospital patient counts to see how your region is doing and watching death counts to see the final toll that COVID-19 has taken in your community.

  • Confirmed death

    There are two ways that a public health agency may count COVID-19 deaths. The agency may track the outcomes of people who have confirmed cases, their infections confirmed by PCR testing. Alternatively, the agency may track the death certificates for its population and tally the certificates that list COVID-19 as a cause of death.

    Confirmed deaths tend to refer to COVID-19 deaths identified through the first method: If someone receives a positive PCR test result, they become a COVID-19 case, and if they pass away while infected, they become a COVID-19 death.

  • Probable death

    When COVID-19 deaths are tallied according to test results, a patient who did not receive a positive PCR test result but did receive a positive antibody or antigen test, exhibited symptoms of the disease, or had come into contact with an infected person, may be included in a count of probable deaths. Probable deaths may also include individuals for whom COVID-19 was a listed cause of death on their death certificate, depending on a particular public health agency's definition.

  • Excess deaths

    COVID-19 has had a massive impact on America's population, with over 180,000 lives lost to the disease. But this number is likely far below the true number of lives lost: many Americans likely contracted COVID-19 but remained undiagnosed because of limited testing access, or died due to the immense impact this disease had on our health care system and economy.

    One way to capture the scope of this true toll is by examining excess deaths, the number of deaths occurring in a particular window of time as compared to the number epidemiologists expect based on previous years. The CDC reports excess death estimates for every U.S. state; in some states, such as New Jersey, over 20% more people have died in February through September of this year compared to previous years.

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