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Why Has the Flu Disappeared?

With COVID-19 still dominating headlines, influenza (flu) has been conspicuous in its absence, especially during what is typically peak flu season. The U.S. Centers for Disease Control and Prevention (CDC) tracks influenza (flu) and pneumonia deaths weekly through the National Center for Health Statistics (NCHS) Mortality Reporting System.

It also creates a preliminary estimate of the burden of seasonal flu, based on crude rates of lab-confirmed flu hospitalizations. Such estimates are intended to give an idea of how many people have been sick from or died from the flu in any given season — that is, except for 2020.

“April 4, 2020, was the last week in-season preliminary burden estimates were provided,” the CDC wrote on its 2019-2020 U.S. flu season webpage.1The reason the estimates stopped in April is because flu cases plummeted so low that they’re hardly worth tracking. In an update posted December 3, 2020, the CDC stated:2

“The model used to generate influenza in-season preliminary burden estimates uses current season flu hospitalization data. Reported flu hospitalizations are too low at this time to generate an estimate.”

They also added, “The number of hospitalizations estimated so far this season is lower than end-of-season total hospitalization estimates for any season since CDC began making these estimates.”3

Flu Deaths Plummet While COVID Cases Rise

In late summer 2020, warnings surfaced that there might soon be a “twin-demic” of flu and COVID-19 that would decimate the globe.4 So far, this hasn’t panned out. In the U.S., the CDC reported that the percentage of respiratory specimens submitted for influenza testing that test positive decreased from greater than 20% to 2.3% since the start of the pandemic.

As of September 18, 2020, they noted that positive influenza tests have “remained at historically low interseasonal levels (0.2% versus 1 to 2%).”5Further, from September 29, 2019-February 29, 2020 to March 1-May 16, 2020, the CDC noted a 98% decrease in influenza activity.6

Similar drops have been observed worldwide, including in the Southern Hemisphere countries of Australia, Chile and Southern Africa, which often serve as sentinels for influenza activity in the U.S.

All three areas had very low influenza activity during June to August 2020, which is their peak flu season. From April to July 2020, only 33 influenza positive test results were detected in Australia; 12 in Chile; and six in South Africa, for a total of 51 positive tests. For comparison, during April to July in 2017 to 2019, 24,512 specimens tested positive for influenza.7

It was initially thought that the steep drops in influenza activity were due to decreased testing, since people with respiratory symptoms likely received COVID-19 tests instead. However, according to the CDC, public health officials have made a concerted effort to test for flu, and even though “adequate numbers” have been tested, little to no flu virus has been detected.

In Australia, meanwhile, they tested “markedly more specimens for influenza” this season than usual, yet still detected very few cases of flu.8 So what happened to the flu?

CDC Tracking Combines COVID, Flu and Pneumonia Deaths

The “COVID” deaths the CDC has been reporting are actually a combination of pneumonia, flu and COVID-deaths, under a new category listed as "PIC" (pneumonia, Influenza, COVID).

Their COVIDView webpage, which provides a weekly surveillance summary of U.S. COVID-19 activity, states that levels of SARS-CoV-2, the virus that causes COVID-19, and “associated illnesses” have been increasing since September 2020, while the percentage of deaths due to pneumonia, flu and COVID-19 has been on the rise since October.9

As noted by professor William M. Briggs, a statistical consultant and policy adviser at the Heartland Institute, a free-market think tank, in the video above, “CDC, up until about July 2020, counted flu and pneumonia deaths separately, been doing this forever, then just mysteriously stopped … It’s become very difficult to tell the difference between these,” referring to the combined tracking of deaths from “PIC.” They’re even using PIC to state that cases are above the epidemic threshold:10

"Based on death certificate data, the percentage of deaths attributed to PIC for week 49 was 14.3% and remains above the epidemic threshold.

The weekly percentages of deaths due to PIC increased for seven weeks from early October through mid-November and are expected to increase for the most recent weeks as additional data are reported. Hospitalization rates for the most recent week are also expected to increase as additional data are reported."