Asymptomatic spread of COVID-19 has been one of the greatest unknowns of the pandemic. It’s also been a source of some pretty major controversy this week after an official with the World Health Organization said asymptomatic people “rarely” spread the virus — then immediately walked it back.
These are big, thorny questions, with profound public health effects. (Some people immediately used the World Health Organization claim to justify not wearing a mask or staying socially distant.) How often do people spread the virus when they don’t have any symptoms? And how many of us may be walking around with the new coronavirus and never really know?
Also, how do kids — sometimes called the “silent spreaders” of COVID-19 — fit into all of this?
Here’s what scientists know (and don’t!) about kids and asymptomatic spread of COVID-19:
We really don’t have good numbers on how common it is.
Several months into the pandemic, researchers still do not know with any kind of certainty how many people are asymptomatic carriers of the virus. The Centers for Disease Control and Prevention recently estimated it was around 35%. Oh, but there was also the widely covered study that found that more than 80% of people infected with COVID-19 on a cruise ship showed no symptoms.
The numbers, in other words, are all over the place.
Similarly, it’s not clear at this point how much asymptomatic carriers drive new cases. Experts say it is possible — possible! — that people who have COVID-19 and never really develop any symptoms are not big spreaders of the virus.
“The vast majority of children who have asymptomatic detection, and never go on to get sick, have exceptionally low concentrations of the virus in their respiratory secretions,” said Dr. Susan Coffin, clinical director of the infectious diseases division with Children’s Hospital of Philadelphia (CHOP). “We can use information from very large studies done in all ages of people to demonstrate that the vast majority of people who have such low concentrations of the virus are not capable of transmitting it.”
The terms “asymptomatic” and “pre-symptomatic” are ... blurry.
One contributing factor to the debate around how many people are “asymptomatic” — and how much they’re contributing to the virus’ spread — is confusion around what the term means exactly. Typically, experts use it to describe someone who has COVID-19, but never displays symptoms.
But there are also people who are infected and have no symptoms for a few days — during which time they might be out, unwittingly infecting others — before they come down with more obvious signs of the virus themselves. Are those people asymptomatic spreaders? Pre-symptomatic? People aren’t always using the same language, which can lead to even greater confusion.
Are kids are actually “silent spreaders”?
When the earliest studies on kids and coronavirus emerged, many media outlets and parents heard the message that kids generally experience much milder symptoms, if any, and kind of ran with it. Soon, we were hearing that coronavirus “spares most kids.” Or that children are “covert spreaders” who never notice they’re actually infected.
But we still just do not have enough data to say definitively whether kids are more likely to be asymptomatic carriers of COVID-19. Or whether asymptomatic kids are likely to infect others. Or how this compares to what’s happening among adults.
At CHOP, for example, all children who have a scheduled medical procedure are now routinely tested for COVID-19, Coffin said.
“What we now know is somewhere around 1 to 2%, at this moment, in Philadelphia, have what looks like an asymptomatic infection with coronavirus,” she said.
But roughly 10% of women delivering babies in Philadelphia have asymptomatic coronavirus, Coffin said. And researchers have no idea why the numbers appear higher in women than kids at this point.
“I do really sympathize with groups like the WHO who are trying to answer questions that are being asked in good faith, like, ‘What is the number?’ Because it’s so based upon the place where the information is coming from, and what the level of viral activity is,” said Coffin. The type of test being used and the patient population being tested can lead to very different findings.
There were several studies early on that found “the rate of spread and the rate of positivity for kids was far lower than for adults,” said Dr. Sandra Kesh, an infectious disease specialist with Westmed Medical Group. “Some places like Switzerland, for example, latched onto that concept of ‘Maybe this is something we don’t have to worry about in kids as much.’”
“But it’s very hard to draw any conclusions from these retrospective studies,” she added.
All of which means it is so important to stick to the basics we know work.
Coffin said that researchers are actively setting up broader studies that hope to measure how common asymptomatic detection and asymptomatic spread are, and told HuffPost she expects some of the very preliminary data to emerge in the next few months.
In the meantime, both experts emphasized that it is essential to adhere to the basic prevention measures researchers know are effective in limiting spread, whether a person has symptoms or not: Wear a mask. Wash hands. Keep social distance. When parents make decisions about what level of exposure they’re comfortable with for their children over the summer and into the fall, they should be really deliberate about those choices. (Keep in mind, too, that a small subset of children who get COVID-19 are subsequently affected by pediatric multisystem inflammatory syndrome, which can be serious and often arises in children who’ve had limited or no symptoms of COVID-19 itself.)
“As soon as you say that kids are not a major vector of disease, everyone starts to relax. The playdates start, and that’s when you’re going to start to see an uptick,” said Kesh.