Influenza Numbers: April 2, 2022

During the COVID-19 pandemic, the Centers for Disease Control and Prevention (CDC) has suspended data collection and evaluation of U.S. influenza cases for the 2020-2021 flu season.

Therefore, current statistics may not fully reflect influenza activity. For example, cases and deaths may be underestimated, and data in some states may be inconsistent or delayed.

During any flu season, the data reported by the CDC weekly are preliminary and subject to change as new information becomes available.

As of April 2, 2022, the CDC reported an increase in influenza-like illness (ILI) activity in much of the United States. At the end of the week of March 26, flu activity continued across the country.

The number of people going to the doctor or hospitalized for respiratory illnesses has been increasing in recent weeks. Influenza is responsible for some of these cases. Other respiratory viruses are also spreading around, making people sick.

Centers for Disease Control and Prevention

Clinical laboratories in the United States tested 45,280 influenza virus samples, of which 6.5% were positive. Of the positive results, 99.2% were for influenza A.

U.S. public health laboratories also report data on sample testing to the CDC. Of the 12,629 samples tested, 339 were positive for influenza. Influenza A accounts for 100% of influenza-positive cases.

2021-2022 Flu Season

On March 4, 2022, the CDC released the first data for the 2021-2022 flu season in the United States. The report is a very early study of the burden of influenza disease in the United States. Here are the estimates the CDC has made so far:

  • Influenza illness: 3,500,000 to 5,800,000
  • Influenza hospitalizations: 34,000 to 69,000
  • Influenza deaths: 2,000 to 5,800

As more data is collected and analyzed, the conclusions drawn by the CDC may change.

Different strains of influenza

Influenza patterns vary depending on the particular strain of influenza circulating in a given year, as well as human behavior. For example, some of the changes brought about by the pandemic — such as wearing masks and social distancing — slowed the spread of the flu last year.

Another factor that affects flu patterns is vaccination. The annual flu shot is a safe and effective way to help curb the spread of the flu and prevent hospitalizations and deaths.

flu vaccine dose given

As of Dec. 17, the CDC reports that more than 174 million doses of flu vaccine have been distributed in the U.S.

What information do countries report?

CDC tracks LIL activity levels in each state and provides weekly influenza surveillance reports. LIL activity levels are defined as follows:

  • Minimum (Levels 1-3)
  • Low (Grade 4-5)
  • Moderate (Grades 6-7)
  • High (Grades 8-10)
  • Very High (Grades 11-13)

State health departments track influenza data provided by hospitals, clinics, clinical laboratories and medical facilities. These reports can include information such as the number of flu tests performed, the positivity rate, and the number of flu-like illnesses providers have seen in patients they treat.

Why are some flu seasons worse than others?

What can the data tell me about flu activity in my state?

ILI activity data can give you an idea of ​​how many people in your state are experiencing respiratory symptoms.

If activity levels are high in your area, it could mean the flu is “spreading around” in your community. You can be more careful and take precautions, such as washing your hands often and getting the flu shot, to help reduce your risk of getting sick.

If you have flu-like symptoms yourself, call your doctor to see if you should get tested. In the meantime, you can take antiviral medications like Tamiflu to help reduce symptoms. You can stop the spread by wearing a mask and avoiding close social contact.

How are flu data different from COVID-19 data?

The flu and COVID-19 are different, although they do have similar symptoms, so it can be difficult to tell them apart. One of the key ways we can track all the data is by testing symptomatic people to see if they have the flu, COVID, or other types of respiratory illness.

Both clinical laboratories (such as those used in doctors’ offices and hospitals) and public health departments test samples for signs of flu, but each has different goals.

Clinical laboratories are more inclined to provide a diagnosis of influenza (or to rule out influenza), while public health laboratories are looking at larger trends in influenza disease—for example, which subtypes of influenza are circulating, and how fast flu cases are increasing in different places and among different groups of people.

Public health departments often test samples that have already been tested in a clinical laboratory for a diagnosis, which is why CDC tracks each laboratory-tested sample separately to ensure the number does not duplicate (if it does, it could be a sign of flu activity in the community). seems to be more than it actually is).

Some flu test samples may also be tested for COVID at the same time, or, if the flu test is negative, a COVID test may be required next. This may be more common in winter, when the two viruses end up spreading at the same time.

Eventually, we may have a recurring “coronavirus season,” like the annual flu season. Currently, public health authorities are trying to track the two diseases as they spread in the community and report the data separately.

COVID and the flu