Newswise — LOS ANGELES (April 21, 2020) -- One of the mysteries of COVID-19 is why children are much less likely than adults to be harmed by the disease. To answer this question, Cedars-Sinai 's Newsroom spoke to Priya Soni, MD, Cedars-Sinai Pediatric Infectious Disease specialist.
"Not only are fewer children testing positive for COVID-19," said Soni, "but those that do test positive are likely to have milder cases."
And that is the opposite of most viruses.
"There is no other respiratory virus that we know, that affects adults so much more severely than infants," Soni said. "For example, when a child gets a viral infection there are usually more intense symptoms, accompanied by high fevers. In the case of COVID-19, it's the adults who are getting the high fevers, having severe complications and even dying."
Soni says U.S. studies confirm the COVID-19 data from China and Italy, that show children represent only around 2% of total infections in the population. There are many theories but no one clear answer to the question of why.
One theory is that because children have young immune systems, and they do not develop the very aggressive immune response known as a cytokine storm that adults form when they get the virus. It is that intense reaction to the virus that helps perpetuate damage in the lungs and other organ systems, often irreversibly harming adult patients.
Another theory that applies to babies is that maternal antibodies transferred from the placenta during the third trimester as well as antibodies found in mothers breast milk may offer protection from the virus especially within the first year of life. There is no evidence of the virus being transferred via breast milk.
Some children already in daycare and school are exposed to many novel respiratory infections. This may cause them to have a higher baseline level of antibodies against other respiratory viruses and could be offering some protective effect.
One worrisome note, is that children can be infected but not show any symptoms, or have such mild symptoms that it can be perceived as a common childhood virus. In fact, Soni says children can unknowingly pass on the virus to adults.
"Children and young adults often feel invincible," Soni said, "but even though they may be feeling fine, they must still take the same precautions as adults to play their part in stopping this pandemic. This is why school closure is such an important piece of controlling rapid spread of this infection."