Coronavirus Chronicles — What Does Presymptomatic Mean?

For a number of complicated reasons, some time will pass before science grasps the relationship between children and COVID-19. We are barely starting to detect the foggy outlines of how it affects adults… or at least, some adults, under certain conditions.

But as soon as children are brought into the equation, the picture becomes very murky. The relationship between the disease and its victims seems to operate under a whole different set of rules, and researchers are frantic to make sense of the conflicting signals. At this time, there does not seem to be much solid information to convey about children. At most, we can devote some attention to what seems to be happening with adults, but the details about what’s going on with kids are far from known.

At one stage, a feature of coronavirus journalism was a kerfuffle over terminology, where confusion is understandable because the temporal dynamics of the disease are all over the map. Two words that have been bandied about extensively are presymptomatic and asymptomatic.

Timing is everything

Some victims are obviously sick quite soon, but others give no clue. Apparently, “presymptomatic” is a time period that may last as long as two weeks. That is considered the outside limit on when they “should” develop discernible symptoms. And yet, many do not seem to have anything wrong with them. Looking like anybody else — looking, in fact, just like healthy people — they walk among us, because they are us. But make no mistake, a presymptomatic person can contain a boatload of virus, and actively (though unknowingly) spread it around.

But if they don’t develop symptoms, if they feel okay and look okay and are not febrile or in pain — while testing positive — the person then graduates to “asymptomatic.” They have the virus! They just don’t have the aches or the disordered gut or any of the other variegated multitude of possible symptoms.

Eric Topol, M.D., of the Scripps Research Institute, echoes the sentiment. “We know presymptomatic people are highly infectious, and they’re responsible for a lot of the virus’s spread.” Journalist Markham Heid cites evidence that presymptomatic people may be even more likely to transmit the disease than those who have symptoms, maybe because we don’t shy away from them.

Appearances can be deceiving

The concept to hold onto is, whatever they are called, they can be very infectious during any stage of the disease process. A second and equally important concept is to maintain compassion. If a person has no symptoms — and some have never even been caught running a fever! — they don’t know they are sick. They might be blamed for not wearing a mask just in case they have the COVID, but they can’t be blamed for not knowing they caught it.

Ed Taboada, Ph.D., who knows about molecular biology and evolutionary biology, explains that even when people go on to develop actual symptoms, they are paradoxically carrying the highest viral loads during the presymptomatic stage. The clear message here is that a hale and hearty demeanor can be one of nature’s little deceptions, and no one should be trusted.

They might just be having an incubation period, and even though they do not feel personally inconvenienced, the disease might very well be quietly multiplying inside them. Taboada says,

There is one often-cited study […] in which they ascribed an estimate of 44% of secondary infections to contacts that occurred during the index case’s pre-symptomatic stage. As per the paper: “We observed the highest viral load in throat swabs at the time of symptom onset, and inferred that infectiousness peaked on or before symptom onset…”

Same information, different phrasing:

We now know that COVID-19 patients have the heaviest viral load — and appear most infectious — at the onset of symptoms, not at the end. People who haven’t yet developed any symptoms, and therefore wouldn’t show up in the CDC’s temperature checks, are responsible for more than 40% of the virus’s spread. And only about 45% of cases early in an infection will develop a fever.

Your responses and feedback are welcome!

Source: “What You Need to Know About Asymptomatic Spread of Covid-19,”, 06/10/20
Source: “What is the evidence of asymptomatic transmission of COVID-19 where symptoms NEVER manifested?,”, 06/22/20
Source: “The CDC Lost Control Of The Coronavirus Pandemic. Then The Agency Disappeared,”, 06/24/20
Image by Florida Guidebook/CC BY 2.0

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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.
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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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