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Tom Kertscher
By Tom Kertscher July 26, 2021

Large-scale testing, not individual testing, tells when delta variant causes COVID-19

If Your Time is short

  • Routine tests that determine whether an individual has COVID-19 do not reveal whether the disease was caused by the delta variant — mass testing of national COVID-19 samples does.

Public health experts say the delta variant of the SARS-CoV-2 coronavirus appears to be twice as contagious as the original coronavirus, and has become the dominant strain in the United States.

So, we must have a test that diagnoses this new mutation, right?

With a rhetorical question, a meme that shows a pensive Albert Einstein doubts the existence of the variant by claiming there is no test for it, saying:  

"SINCE THERE IS NO ‘DELTA VARIANT’ TEST EXACTLY HOW ARE PEOPLE BEING DIAGNOSED WITH DELTA VARIANT."

The post was flagged as part of Facebook’s efforts to combat false news and misinformation on its News Feed. (Read more about our partnership with Facebook.)

No one is being diagnosed with the delta variant, or any other variant. Routine tests that individuals receive to determine whether they have COVID-19 do not reveal whether the disease was caused by the delta variant. 

 

But through what is known as genomic sequencing, public health officials examine samples of cases to estimate what percentage were caused by delta.

Genomic sequencing from a positive test sample, said Stephen Morse, professor of epidemiology at Columbia University Medical Center, "would tell you unequivocally what variant infected that person."

Featured Fact-check

What is a variant? What is the delta?

A variant of the coronavirus that causes COVID-19 is one that has mutated in a way that bolsters its spread or severity compared with the original strain that emerged in Wuhan, China. Public health officials have noted four "variants of concern" circulating in the United States, including delta, formally called B.1.617.2. Discovered in India in December 2020 and in the U.S. in March 2021, it is the most transmissible of the four variants. While it is not yet known if the delta produces more serious illness, it threatens to accelerate the spread of the pandemic.

If individual testing doesn’t reveal delta, how do we know it is in play?

The federal Centers for Disease Control and Prevention explains how it tracks variants by analyzing some 750 samples per week from state health departments and other public health agencies and making estimates:

"The SARS-CoV-2 genome encodes instructions organized into sections, called genes, to build the virus. Scientists use a process called genomic sequencing to decode the genes and learn more about the virus. Genomic sequencing allows scientists to identify SARS-CoV-2 and monitor how it changes over time into new variants, understand how these changes affect the characteristics of the virus, and use this information to better understand how it might impact health."

In the U.S., delta is the cause of more than 80% of new COVID-19 cases, according to the CDC.

Our ruling

Individuals are not being diagnosed with the delta variant.

Routine individual tests don’t reveal whether COVID-19 was caused by the delta variant. Scientists use genomic sequencing to determine what percentage of cases were caused by the variant. 

This post contains an element of truth, but ignores critical facts that would give a different impression. 

We rate it Mostly False.

Our Sources

Facebook, post, July 26, 2021

Email, Kent State University epidemiologist Tara Smith, July 26, 2021

Email, Stephen Morse, professor of epidemiology at Columbia University Medical Center, July 26, 2021

PolitiFact, "The coronavirus variants: What you need to know," July 7, 2021

PolitiFact, "Data showing lower death rate for coronavirus delta variant doesn’t mean it’s less dangerous," July 7, 2021

U.S. Centers for Disease Control and Prevention, "Variant Proportions," accessed July 26, 2021

U.S. Centers for Disease Control and Prevention, "What is Genomic Surveillance?", June 17, 2021

U.S. Centers for Disease Control and Prevention, "CDC’s Role in Tracking Variants," June 17, 2021

Yale Medicine, "5 Things To Know About the Delta Variant," July 22, 2021

American Lung Association, "All You Need to Know About the Delta Variant," July 16, 2021

WFAA.com, "If you get COVID-19, will you know it's the Delta variant? Here's why you likely won't," July 22, 2021

Deseret News, "Is there a specific COVID-19 test for the delta variant? What you need to know," July 20, 2021

Raleigh News & Observer, "Few COVID cases are tested for delta variant. Here’s why NC officials trust the numbers," July 23, 2021

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Large-scale testing, not individual testing, tells when delta variant causes COVID-19

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