What to know
- SARS-CoV-2, the virus that causes COVID-19, continues to cause serious illness, and respiratory syncytial virus (RSV) can be dangerous for infants and older adults.
- Using a model similar to one developed for flu, CDC is sharing in-season COVID-19 and RSV disease estimates for numbers of medical visits, hospitalizations, and deaths.
- These estimates can help public health agencies, policymakers, and the public make informed decisions about prevention strategies.
Summary
What CDC knows
CDC collects data on laboratory-confirmed COVID-19- and RSV-associated hospitalizations from a network of hospitals serving about 10% of the U.S. population. Scientists use these data to estimate the burden of each illness for the whole country, including the number of people who went to an outpatient healthcare provider, were hospitalized, or died because of these illnesses during a specific time.
What CDC is doing
CDC recently published the first estimates of current season burden for COVID-19 and RSV, reporting the burden of illness since October 1, 2024. CDC will update the estimates, which will be cumulative, every week. CDC has published similar estimates for flu for many years.
New COVID-19 and RSV estimates can help shape prevention efforts
It is not possible to know exactly how many people get sick from COVID-19 or RSV. That's because not everyone who gets COVID-19 or RSV will get tested or seek medical care. Also, COVID-19 and RSV are not nationally notifiable diseases. This means only cases that lead to hospitalization are reported to CDC. Because of this, CDC uses statistical models that are based on inputs from continually updated surveillance data and data from the latest scientific studies. These statistical models estimate the national impact, or burden, of COVID-19 and RSV.
This is the first time CDC has provided a range of in-season burden estimates for COVID-19 and RSV. Currently, these estimates show how COVID-19 and RSV have affected Americans since October 1 of this year. For example, CDC estimates that 72,000–120,000 people were hospitalized for COVID-19 between October 1 and December 7, 2024. This shows that COVID-19 still causes a substantial number of serious illnesses, even when overall levels of COVID-19 activity are low compared to earlier periods. People can use this information to help them make informed decisions about their healthcare, such as vaccination, testing, and treatment.
These estimates can help public health officials promote prevention measures and plan for COVID-19 and RSV impacts on healthcare systems to ensure that Americans can continue to get the healthcare they need during times of widespread respiratory illnesses. The estimates will also help us compare the burden associated with COVID-19 and RSV year over year and compare it to other respiratory illnesses, like flu.
How burden estimates work
CDC has been estimating flu disease burden since 2010 using mathematical models based on combined hospitalization surveillance, lab data, healthcare seeking behavior, and deaths. The new RSV and COVID-19 burden estimates were developed using a similar approach.
The first step in estimating burden uses the hospitalization data from RESP-NET, a CDC surveillance network that includes COVID-NET, RSV-NET, and FluSurv-NET. This network collects data on hospitalizations for laboratory-confirmed flu, COVID-19, and RSV from a network of hospitals serving about 10% of the U.S. population. CDC uses these data to estimate nationwide hospitalizations associated with these viruses.
The estimates of hospitalizations associated with these viruses are then used to estimate additional measures of burden from these illnesses, including the number of outpatient visits and deaths and, for flu and COVID-19, how many people got sick.
Models help us better understand COVID-19's impact
COVID-19 death data are an example of how useful statistical modeling can be. The accuracy of COVID-19 reporting of deaths can be affected by many factors. COVID-19 may lead to death from complications such as stroke or pneumonia. Because of this, these deaths may be attributed to the complications of COVID-19 instead of COVID-19 itself. Also, patients aren't always tested for COVID-19, and not all COVID-19 deaths occur in the hospital. These factors can lead to underreporting COVID-19 deaths. That's why modeling strategies are commonly used to estimate total COVID-19-associated deaths; they can help account for factors that influence reporting of deaths.
Want to know more about the methods behind the science? Take a look at these pages:
The current respiratory virus season
Preliminary U.S. COVID-19 and RSV burden estimates since October 1, 2024, are available on CDC's website and will be updated weekly on Fridays. This year's and previous years' flu disease burden estimates are also available.
Here are a few key numbers for the current respiratory virus season:
- An estimated 72,000–120,000 people were hospitalized for COVID-19 during October 1–December 7, 2024.
- An estimated 22,000–45,000 people were hospitalized with RSV during October 1–December 7, 2024.
- An estimated 15,000–33,000 people were hospitalized for flu during October 1–December 7, 2024.
Three things to note about the estimates:
- Because of reporting delays, estimates are preliminary and may change as more data become available. As CDC gets new data each week and updates the previous estimates.
- Last year's estimates will be updated if more data become available. These estimates will remain preliminary until all data for that year are finalized, which is usually within 2 years.
- CDC provides a range around the most likely numbers, rather than providing a specific number. A range better represents the uncertainty in the estimates.
Preventing severe illness this respiratory virus season
Immunizations are the best way to prevent serious illness from COVID-19, RSV and flu. Here's who should get them:
- COVID-19: CDC recommends that everyone ages 6 months and older get the 2024–2025 COVID-19 vaccine. Staying up to date on COVID-19 vaccines is especially important for those at highest risk of severe illness.
- RSV: Babies and older adults need protection from RSV.
- There are two options recommended to protect infants from severe RSV:
- a maternal RSV vaccine given during pregnancy or an RSV antibody given to infants after birth. Most babies don't need both.
- The RSV antibody is also recommended for a small group of young children ages 8–19 months who are at increased risk for severe RSV.
- a maternal RSV vaccine given during pregnancy or an RSV antibody given to infants after birth. Most babies don't need both.
- RSV vaccines are recommended for all adults ages 75 and older and adults ages 60–74 who are at increased risk for severe RSV. The RSV vaccine is given as a single dose. If you have received an RSV vaccine already, you do not need to get another RSV vaccine at this time.
- There are two options recommended to protect infants from severe RSV:
- Flu: Everyone 6 months and older should get a flu vaccine every season, with rare exceptions.
Other actions can also help prevent the spread of respiratory viruses—for example, frequent handwashing, covering coughs and sneezes, and staying home when you are sick. CDC's respiratory virus guidance gives more information on how you can help prevent respiratory viruses.