Preliminary Estimates of COVID-19 Burden

Importance of understanding COVID-19 burden

While COVID-19 is no longer a national public health emergency, SARS-CoV-2 still makes people sick. In fact, for many in the United States each year, it can lead to illness, hospitalization, and death.

Understanding the burden of COVID-19 helps:

• Describe how infection is impacting people across the nation.

• Establish benchmarks to compare the burden associated with COVID-19 year-over-year and with diseases caused by other respiratory viruses, like influenza and respiratory syncytial virus (RSV).

Why CDC estimates the burden of COVID-19

It is not possible to know the exact number of people who have experienced illness from COVID-19 in the United States, because not everyone who contracts COVID-19 will seek medical care or get a test for SARS-CoV-2. COVID-19 also is no longer a nationally notifiable disease, meaning COVID-19 cases are no longer reported to CDC. For these reasons, CDC surveillance (or tracking) systems cannot identify all COVID-19 illnesses in the United States. Therefore, CDC uses continuously updated surveillance data, data from the latest scientific reports, statistical and mathematical modeling to estimate the burden of COVID-19 on the US population.

When sharing estimates of COVID-19 disease burden, CDC provides a range around the most likely values of COVID-19 burden to better represent the uncertainty in the estimates.

CDC estimates the burden based on continuously collected surveillance data on patients with laboratory-confirmed COVID-19-associated hospitalizations. These data are derived from the Coronavirus Disease 2019 (COVID-19)-Associated Hospitalization Surveillance Network (COVID-NET), a surveillance platform that captures data from hospitals that serve about 10% of the U.S. population.

Find more details on how COVID-NET data are used to estimate illnesses, outpatient visits, hospitalizations, and deaths in the United States: How CDC Estimates the Burden of COVID-19 in the US.

Each week CDC estimates a range (i.e., lower estimate and an upper estimate) of COVID-19-associated hospitalizations that have occurred since the beginning of a twelve-month surveillance period. This can help public health officials understand and plan for COVID-19 related impacts on healthcare systems and promote prevention measures.

Data are preliminary and estimates are subject to change as more data become available. Rates for recent COVID-19-associated hospital admissions are subject to reporting delays; as new data are received each week, previous rates are updated accordingly. Yearly preliminary estimates will be updated year-to-year and are considered final when all data for that year are available (usually within 2 years of the preliminary estimate).

Current year COVID-19 hospitalizations

Interpreting the cumulative burden of COVID-19

Preliminary burden estimates are provided weekly using data from October 1 of the current year once sufficient data are available to estimate the burden.

The cumulative estimates of COVID-19 burden are preliminary and change week-by-week for the current year as updated COVID-19 hospitalization data are reported to CDC via COVID-NET. Updated reports include both new hospital admissions that have occurred during the reporting week and patients admitted in previous weeks that may not have been included in earlier reporting to CDC.