WASHINGTON — Variations of Influenza circulate in the United States every winter. For the last few flu seasons, cases have hovered between 25-45 million cases. But this year, many people feel like the flu seemed to almost disappear.
Viral tweets claim that cases dropped from 38 million to about 2,000, and widespread face mask usage is the reason.
Verify researchers dug into the numbers to see what we could find; and although the data is incomplete, we found a significant change in the flu burden in the United States this winter.
THE QUESTION
Did flu cases fall dramatically from the 2019-20 flu season to the 2020-21 flu season? Is masking the reason?
THE SOURCES
Centers for Disease Control and Prevention (CDC)
THE ANSWER
Yes, flu cases plummeted. But, the CDC says there are several reasons for this, and it's not possible to pinpoint which preventive measure was the most influential because they were used simultaneously (masking, distancing, vaccinations, etc.).
WHAT WE FOUND
The 2019-2020 flu season saw an estimated 38 million influenza cases and 22,000 deaths. The CDC calculates these estimates every year based on their direct testing data, hospitalization records, and a number of complex mathematical models which have been used and perfected over the years.
The estimates start with the CDC's surveillance network, which collects hospitalization statistics from about a dozen state and local health departments and about 9% of hospitals in the U.S. Case numbers are then estimated based on those stats.
As of June 1, the CDC is reporting just 1,899 positive tests in clinical labs and 251 in public health labs since the week of September 27, 2020. But, the CDC has not released an official estimate of influenza burden for the most recent flu season.
"Because influenza activity was so low during the 2020-2021 season, the laboratory-confirmed influenza-associated hospitalization rates used in the mathematical model of influenza for this past season were too low to calculate estimates for the 2020-2021 season," a CDC spokesperson told VERIFY via email.
So while we can't say the exact number of flu cases in the U.S. during this season, the drop was drastic — from tens of millions to low thousands.
Similar to case data, death data is also incomplete. But, based on the numbers reported by the National Center for Health Statistics, there were only 686 reported influenza deaths between the week of September 27, 2020 and the week of May 22, 2021. Of those, only one was a child.
Asked whether we can credit widespread masking for the plummeting flu cases, a CDC spokesperson said it will be difficult to hammer down which specific preventive measures contributed the most. It is likely a combination of most COVID-19 prevention tactics that kept a bad flu season at bay: decrease in travel, distanced work and school, masking, social distancing, etc.
They pointed out as well the U.S. saw record high flu vaccinations: nearly 194 million doses. "The more people who are vaccinated against flu, the more people will be protected from flu," a spokesperson told us.