Coronavirus Chronicles — Body Heat Goes Back to School

Scientists are enamored of testing for multiple reasons. Theoretically, testing reveals who has the virus and who does not. That is a big subject, for another day. The exciting thing about testing is how it unveils misconceptions, like the one that the medical profession labored under for the first few months of the coronavirus crisis.

Even in late June, an American Academy of Pediatrics document said, “According to the CDC (Centers for Disease Control), children […] may be less likely to present with fever as an initial symptom…” The thing is, “may” and “likely” are what some call weasel words, the kind that leave plenty of wiggle room. Strictly interpreted, they mean that children may indeed be likely to spike a temp.

This matters a lot

Obesity prevention is only one of a multitude of reasons for wanting the kids back in school. But if there are to be in-person classes, someone has to decide who gets in. The desire to base the decision on temperature is understandable. Fever seems so objective and verifiable. Many businesses and institutions — including schools — rely on touch-free temperature instruments to determine who should be admitted to the premises.

What can go wrong? Several things, including device malfunction and operator error. A person might have a fever for some different medical reason. They might have been running to catch a plane. A person might be taking medication that hides the underlying fever. Apparently, certain other drugs can cause temperature elevation.

In consequence, people who should not be denied are kept out of places, or needlessly assigned to isolation. People who should not be admitted, do get in. For a hard-headed assessment of thermometer guns, check out this Business Insider report. It includes the words “notoriously not accurate” and implies that the use of the devices might be just another form of security theater.

In mid-May, the CDC also said,

The list of symptoms of COVID-19 infection has grown since the start of the pandemic and the manifestations of COVID-19 infection in children, although similar, is often not the same as that for adults.

In the interim, reports have come in of large-scale, random testing where it has been shown that not even half the people who test positive for COVID-19 have fevers. Other reports give an even worse impression. In her article on, Alexandra Sifferlin wrote,

[One] one unique aspect of the virus that causes Covid-19 is that infected people are contagious in the period before they start to develop symptoms (if they do eventually develop them).

New data released from the clinical testing company Color found that among 30,000 people tested for Covid-19, 300 tested positive. Among those people […] 12% had a high fever.

While identifying 12% of people who might be at risk is not nothing, it’s also clear that a high fever is not necessarily the most reliable metric to screen people for Covid-19.

Consequently, it turns out that we really don’t know much — except that body temperature is a maddeningly unreliable indicator of disease, and basing the pass/fail system on it sounds a bit shaky. Letting kids go to school just because they don’t have fevers sounds pretty risky. Infectious disease and public health worker Ed Taboada wrote,

If one of the major components of your firewall against the virus is a diagnostic test that will catch fewer than half of those people that are infected and infectious, then I would suggest to you that your firewall is a bit of a failure.

Still, the temperature guns are all we have. The June AAP guidance discusses, at length, who (parents, bus drivers, or school personnel) should be taking children’s temperatures each morning, with each possibility owning its drawbacks. But whether the device is wielded by a parent, driver, or teacher, it does not tell the whole story.

Your responses and feedback are welcome!

Source: “COVID-19 Planning Considerations: Guidance for School Re-entry,”, 06/25/20
Source: “Thermometer guns used to screen for coronavirus are ‘notoriously’ unreliable experts say, warning about improper use and false temperatures,”, 02/15/20
Source: “Symptoms of Coronavirus,”, 05/13/20
Source: “What is the evidence of asymptomatic transmission of COVID-19 where symptoms NEVER manifested?,”, 06/22/20
Source: “Taking people’s temperature at airports and restaurants needs to be part of a more comprehensive strategy.”, 06/17/20
Image by MTA of State of New York/CC BY 2.0

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OVERWEIGHT: What Kids Say explores the obesity problem from the often-overlooked perspective of children struggling with being overweight.

About Dr. Robert A. Pretlow

Dr. Robert A. Pretlow is a pediatrician and childhood obesity specialist. He has been researching and spreading awareness on the childhood obesity epidemic in the US for more than a decade.
You can contact Dr. Pretlow at:


Dr. Pretlow’s invited presentation at the American Society of Animal Science 2020 Conference
What’s Causing Obesity in Companion Animals and What Can We Do About It

Dr. Pretlow’s invited presentation at the World Obesity Federation 2019 Conference:
Food/Eating Addiction and the Displacement Mechanism

Dr. Pretlow’s Multi-Center Clinical Trial Kick-off Speech 2018:
Obesity: Tackling the Root Cause

Dr. Pretlow’s 2017 Workshop on
Treatment of Obesity Using the Addiction Model

Dr. Pretlow’s invited presentation for
TEC and UNC 2016

Dr. Pretlow’s invited presentation at the 2015 Obesity Summit in London, UK.

Dr. Pretlow’s invited keynote at the 2014 European Childhood Obesity Group Congress in Salzburg, Austria.

Dr. Pretlow’s presentation at the 2013 European Congress on Obesity in Liverpool, UK.

Dr. Pretlow’s presentation at the 2011 International Conference on Childhood Obesity in Lisbon, Portugal.

Dr. Pretlow’s presentation at the 2010 Uniting Against Childhood Obesity Conference in Houston, TX.

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