Why do children fare better against COVID? Study points to nasal passages

Nasal swabs
Posted at 10:39 AM, Aug 29, 2021
and last updated 2021-08-29 13:39:54-04

SAN DIEGO (KGTV) -- A new study offers one of the most detailed explanations yet to a persistent question of the pandemic: why kids fare so much better against COVID-19 than adults.

The paper in the journal Nature points to molecular differences in the nasal passages of kids and adults.

The researchers found kids’ noses are pre-loaded with immune cells capable of recognizing SARS-Co-V2 before the virus even arrives. Adults largely lack these cells prior to infection and are stuck playing catch-up.

Unlike other respiratory viruses, SARS-Co-V2 is notoriously good at disabling the signaling proteins the body uses to call in reinforcements, allowing it to make copies of itself without a counterattack.

The virus gives the body an “extremely narrow window of opportunity” to respond before it shuts down the alarm system, making early detection critical, the authors wrote.

The study found children’s upper airways are “pre-activated and primed for virus sensing,” allowing them to more rapidly respond to the coronavirus. The paper enumerates the web of cells and genes that are activated when the body launches its opening salvo.

“It's incredibly valuable because it gives us insight into why kids do so well,” said Dr. John Bradley, director of infectious diseases at Rady Children’s Hospital, who was not involved with the study.

Of the 64,383 deaths attributed to COVID-19 in California as of August 18, only 30 have been among children, according to the California Department of Public Health.

“Kids will stop the replication of virus much earlier,” Bradley said. “They handle these infections better than adults on first exposure.”

Doctors have long understood that children generally have superior innate defenses to new viruses than adults. That’s largely out of necessity, Bradley said. Kids encounter viruses that are new to them all the time, so they have a heavily fortified innate immune system.

Like landmines on a battlefield or a high castle wall, these generalized defenses respond to anything the body can identify as a foreign substance.

“Children have huge lymph glands, that's normal,” Bradley said. “As you get older, by the time you are school age or a teenager, they shrink down to adult-size level.”

As children age into adulthood, they encounter fewer new viruses. Their bodies begin to rely instead on the adaptive immune system: white blood cells that have been specially trained for each pathogen, Bradley said.

Now that researchers have identified the specific mechanisms involved in the initial response to SARS-CoV-2, Bradley said scientists can begin to examine the rare cases where kids suffered severe disease and pinpoint the features those children were missing.

That could help doctors better predict the children at greatest risk and ultimately improve treatments, he said.