Viral Posts Distort WHO Guidance on COVID-19 Tests


Quick Take

Dubious web sites and viral posts falsely declare that the World Health Organization modified COVID-19 testing protocols for political causes following Joe Biden’s inauguration and admitted that false-positive instances had been inflating the case depend. The WHO’s steering merely reminded labs to comply with directions offered by every take a look at’s producer.

Full Story

A recent memo from the World Health Organization designed for lab professionals grew to become a serious focus of misinformation — with unreliable web sites and social media customers claiming the company had modified a testing protocol and admitted that COVID-19 instances have been wildly inflated.

But neither of these claims is correct.

Instead, the Jan. 20 memo directed labs facilitating polymerase chain response, or PCR, checks to fastidiously comply with producer directions for testing to stop false constructive and unfavourable outcomes.

The distortions on-line additionally tied the purported change to U.S. politics.

“An Hour After Joe Biden Is Sworn In, WHO Admits Their Testing Grossly Overstates Individuals Testing Positive for COVID,” learn a headline from the Gateway Pundit, a web site recognized for spreading misinformation. The story questioned the motives of public well being companies, asking, “how can these entities ever be trusted again?”

The story was shared greater than 8,000 occasions on Facebook, in accordance with CrowdTangle analytics data.

Another web site, Zero Hedge, which additionally has beforehand unfold falsehoods, equally told readers: “Right On Cue For Biden, WHO Admits High-Cycle PCR Tests Produce COVID False Positives.” That story was shared on Facebook practically 7,000 occasions.

Many posts additionally cited a viral tweet from David Samadi, a urologist and contributor to the conservative information channel Newsmax, whose work in a New York hospital was the topic of a federal investigation into fraudulent Medicare claims. That hospital reached a $12.3 million settlement in late 2019.

In his tweet, which has since been deleted, Samadi mentioned the steering instructed labs “to reduce the cycle count in PCR tests to get a more accurate representation of COVID cases,” as a result of “the current cycle was much too high and resulting in any particle being declared a positive case.” One Facebook submit sharing Samadi’s tweet claimed that the steering proved “they’ve been lying to you about case counts and mortality rate THE WHOLE TIME.”

As we mentioned, the WHO steering implied no such admission. And the memo was an up to date model of 1 issued a month earlier, on Dec. 14, so the concept that it was timed for Biden’s inauguration is improper.

As we’ve defined earlier than, PCR checks work by scanning the RNA in a pattern, resembling a nostril swab, and trying to find the virus RNA. (See our SciCheck article “The Facts on Coronavirus Testing.”)

The PCR take a look at analyzes samples by amplifying a section of the virus’s genetic materials in a sequence of cycles. A pattern with a better viral load, that means extra virus is current within the pattern, would require fewer cycles to detect the novel coronavirus. Lower viral hundreds shall be detected at increased cycles.

There isn’t any common threshold setting or endpoint — “although 40-45 cycles is often used as the endpoint” of a PCR run — Ian MacKay, a virologist in Australia, advised us in an electronic mail. 

The WHO’s Jan. 20 steering mentioned it was requesting that these conducting checks you should definitely learn producer directions “carefully to determine if manual adjustment of the PCR positivity threshold is recommended.”

In a press release to, the WHO mentioned it had acquired 10 reviews since early 2020 about some PCR checks offering each false constructive and false unfavourable outcomes and that “[a]fter thorough investigation, WHO confirmed that the tests were not always being used appropriately and in accordance with the instructions provided by the manufacturer.” 

“In particular, users in laboratories encountered problems with these tests when they did not apply the recommended positivity threshold — this can result in either false negative results (if the threshold applied is lower) or false positives (if threshold is higher),” the WHO mentioned.

MacKay mentioned that drawback “is not a test issue; it’s a human training and experience issue.”

“I suspect this is more a problem for certain countries or jurisdictions where rapid roll-out of new testing labs has occurred; labs that are new to public health testing,” MacKay mentioned. “This would typically involve places that have failed to adequately invest in a good public health laboratory network, to begin with. I don’t think anything shows changing threshold values or less experienced laboratories have driven significant inflation of COVID-19 case counts though.”

Kelly Wroblewski, director of infectious ailments on the Association of Public Health Laboratories, mentioned in a telephone interview that the WHO steering was a easy reminder that if lab professionals deviate from the really helpful producer thresholds they’re “going to over- or under-call the positives or negatives.” She mentioned the problem was not a major concern within the U.S.

In a blog post batting down the misconceptions in regards to the WHO’s steering, MacKay wrote that “this lab-focused advice has been taken by those with malicious intent, or with too little understanding of the topic, and blown it up into something else entirely wrong.”

He additional emphasised to us that “PCR results are not a diagnosis by themselves” — they’re a part of the COVID-19 prognosis. WHO advises they be thought of in context of different components, together with signs and potential publicity to COVID-19.

Understanding Cycle Threshold Values

PCR checks are thought of a gold customary for diagnostics amongst scientists, and whereas false unfavourable and constructive outcomes are doable with any take a look at, false positives from PCR checks should not considered a serious or systemic concern — even constructive outcomes at high-cycle threshold values — specialists say.

For instance, MacKay has observed that, COVID-19 knowledge on checks within the United Kingdom, even lowering the “cycle number by 10 (from, for example, 45 to 35), for the sake of appeasement, the majority of positives would still be uncontroversially positive.”

Matthew Binnicker, a professor of laboratory medication and pathology on the Mayo Clinic, mentioned the true debate over outcomes at high-cycle threshold values isn’t whether or not they’re “false positives.”

“PCR tests are very specific, and these are not false-positives,” he advised us in an electronic mail. “The test is doing what it was designed to do — detect the viral RNA in samples.”

Instead, he mentioned, the stress amongst scientists issues whether or not the values can be utilized “to determine whether someone is, or is not, ‘infectious’” to others. In different phrases, the query isn’t whether or not somebody contracted the coronavirus, however moderately, whether or not that individual is more likely to nonetheless be contagious and needs to be advised to isolate and have their contacts traced. 

“Some would argue that we should be ignoring low-positive PCR results (i.e., those with a high PCR cycle threshold value), as these results may mean that someone is no longer infectious,” Binnicker mentioned.

But, he mentioned, such a outcome might additionally imply that an individual solely very lately grew to become contaminated and has but to hit peak infectiousness.

And, he cautioned, the standard and kind of pattern can even have an effect on what number of cycles are wanted to detect the virus, so it’s not at all times the case {that a} high-cycle outcome means an individual is harboring remnants or solely small quantities of the virus.

Michael Mina, an assistant professor of epidemiology at Harvard University, likewise mentioned getting constructive take a look at outcomes at high-cycle threshold values “doesn’t mean they’re false positive, they’re still actually detecting the SARS-CoV-2 RNA.”

Mina mentioned throughout a name with reporters that the WHO’s memo served as a reminder that “you have to be discerning about how to evaluate” cycle threshold values. “And if you’re going to start using the actual values from the PCR as part of your decision-making, [it’s important] to really know what it is you’re doing.”

For instance, if somebody is asymptomatic and occurred to get a PCR take a look at by means of testing as a part of surveillance in a neighborhood, it could be a low viral load detected at a high-cycle threshold worth — which might imply “you already were infectious and you maybe don’t need to be isolated,” he mentioned.

“But it’s very hard to know that. You need to do repeated testing, you need to take that person and test them again,” he added. “Or, test them with an antigen test. That would be the other way to approach it.” (Antigen checks are a different type of take a look at that can be utilized to shortly establish an lively coronavirus an infection.)

Binnicker additionally famous that, since sufferers who take a look at constructive for COVID-19 can typically proceed to check constructive lengthy after recovering, the Centers for Disease Control and Prevention doesn’t recommend PCR checks be used to find out when somebody is not infectious. Instead, the company advises relying on time and signs to interrupt from quarantine or isolation.

Jessica McDonald contributed to this text.

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