COVID by the Numbers: Spring 2024

Frequently Asked Questions

• How does the CDC get COVID data?

  Throughout the pandemic, states and the U.S. territories reported certain COVID information to the CDC. In the beginning, data were reported daily. Over time, the reporting frequency decreased to weekly updates. By early 2023, some states had stopped updating the CDC with COVID data.

  A lot of this data was collected and reported at the county level. Even when there is not a pandemic, there are certain infectious diseases that states always need to report, meaning that most public health departments are already aware of the need to collect and share data with the CDC.

  That said, the COVID pandemic demanded more from state health departments, and having to collect and report data on COVID cases, deaths, and transmission was not easy.

  For much of the pandemic, all 50 states were reporting to the CDC, as well as specific jurisdictions. For example, New York City reported its own data separate from New York state. 

• What information did states report to the CDC?

  States told the CDC about how many cases of COVID they had in the state, as well as how many people had died from COVID. States reported the total number of cases since they started keeping track (which included both confirmed and probable cases—though not all jurisdictions reported these figures) and the number of new cases and deaths reported within the last seven days. 

  Information about COVID testing, hospitalizations, and the number of people who had recovered was also reported. In some cases, the data was presented as a percentage. In other cases, you might see the data displayed as “the rate per 1,000 people” within a given timeframe. 

  Since each state is not the same size, looking at the number of cases or deaths relative to how many people live in the state tells you more about the spread of the virus than simply looking at the raw data. A high number of cases in a state with a small population would mean something different than the same number of cases in a state that is three times as big.

  States also reported some information that was not accessible to the public; the restricted data contained more specific fields that could potentially compromise patient privacy. This data was more meant for public health officials and researchers. 

  Some states provided data about how communities had been affected by COVID-19. For example, the CDC displayed data that showed how often people were going out in certain parts of the country and related this data on mobility to the level of virus transmission in those areas during specific times.

  Some states also provided information about specific populations, such as healthcare workers and people who are pregnant. 

• How accurate is the data?

  The numbers reported to the CDC are as accurate as a state can provide, though they can change. While the numbers were initially updated daily, there were sometimes lags over the weekend or over the holidays. Some states had backlogs of tests from weeks ago, meaning that the data reported was a little behind the current situation.

  The totals that were reported sometimes included probable (or suspected) cases and deaths that had not been confirmed. However, some places did not report suspected cases or deaths—only those that have been confirmed. Later on, it may have turned out that those cases were not related to COVID after all, in which case those cases would be dropped from the report.

  It’s also important to keep in mind that there are people who get COVID and do not have symptoms. If they aren’t sick and do not realize that they were exposed, they are not likely to get tested. Unless states had the ability to do more widespread testing that included people without symptoms, it’s likely that they were undercounting the total number of COVID-19 cases because asymptomatic people were not included if they did not get a test.

  In some circumstances, people who go to the emergency room for symptoms of COVID might be diagnosed with another illness, like the flu or pneumonia. Data on ER visits that could be related to COVID-19 were not reported by all jurisdictions, however.

  The data that was reported did not look the same coming from all the different hospitals in the U.S. because healthcare systems do not code diagnoses in the same way. In some cases, the coding classification changes which could affect whether a case is counted as a COVID case or not.

  Similarly, deaths from COVID might have been missed if something like pneumonia was listed as the cause of death on a person’s death certificate or in a provider's documentation rather than the death being attributed to COVID.

  There were also situations where a person who was sick or had been exposed to someone with COVID did not seek care or did not have access to tests. 

  It’s also possible that a state counted cases or deaths that actually “belong” to another state’s totals. This can happen if someone lives in one state, travels to another, and gets COVID while they are traveling. 

  Due to these factors, it’s normal for case and death numbers to change—in fact, they are changing often.

• What can I tell about COVID in my state by looking at the numbers?

  There are several pieces of data to consider if you want to understand the COVID situation where you live. While the most straightforward numbers are the total case and death counts, these figures don’t give you the full story. When you’re looking at statistics, context is important.

  It can be more helpful to look at how the number of cases compares to how many tests your state is doing. If your state is not testing many people, the number of positive cases will not really reflect how many people in your state likely have COVID.

  It’s also important to remember that the total numbers—both in terms of testing and confirmed cases—are likely missing people who are asymptomatic. Remember that a person can have COVID-19 without getting sick, but they can still spread it to others without realizing it. 

  Additionally, looking at the totals from the beginning of the pandemic to the present doesn’t tell you the same information as looking at 7-day averages. You can get a better sense of how fast cases and deaths are rising by looking at how the numbers have changed in the last week as opposed to nearly a year.

  If you’re looking at the number of deaths, remember that those numbers are slower to change than the total number of cases. There can be a “lag” between a rise in cases and a rise in hospitalizations or deaths because it takes some time for people to get sick.

• How will new variants affect COVID numbers?

  New variants of the COVID virus are always emerging, as it's natural for viruses to change over time. Researchers follow new variants closely to see if the changes in the viruses may make them more of a threat—for example, they might become better at spreading or resisting vaccines and treatments. Some changes can also make the virus more likely to make people very sick if they catch COVID.

  Learn More Why BA.2.86 Stands Out From Other COVID Variants