September 6, 2022 – Don’t count on a runny nose.
Young children with COVID-19 often have no symptoms at all, even if they have a large amount of the virus in them, according to a new study.
Only 14% of adults who tested positive for SARS-CoV-2, the virus that causes COVID-19, had no symptoms of the disease, compared to 37% of children under age 4, the researchers found.
This raises concerns that parents, daycare centers and preschools may not see the level of infection in apparently healthy young children exposed to COVID-19, wrote lead author Ruth A. Karron, MD, and colleagues in the Journal of the American Medical Association Opened.
The study involved 690 people from 175 Maryland households who were closely monitored between November 2020 and October 2021. For 8 months, they performed online symptom checks every week and PCR tests – which detect the presence of the virus that causes COVID-19 – done with nasal swabs. Those with symptoms submitted more swabs for analysis.
“What was different about our study? [compared with previous studies] was the intensity of our collection, and the fact that we [tested those who did not have COVID symptoms]Karron, a pediatrician and professor in the Department of International Health at Johns Hopkins University in Baltimore, said in an interview. “The fact that we took samples every week meant we could pick up those early infections.”
The study also stands out for its focus on young children, Karron said. All households participating in the study had at least one child up to 4 years of age, with 256 of the 690 individuals (37.1%) in this youngest age group. The other people in the study were 100 children ages 5 to 17 (14.5%) and 334 adults ages 18 to 74 (48.4%).
The youngest were most likely to have no symptoms
At the end of the study, 51 people had tested positive for the coronavirus, 14 of whom had no symptoms. A closer look found that children ages 4 and younger who got COVID-19 were more than twice as likely to have no symptoms as infected adults (36.8% vs. 14.3%).
The relationship between symptoms and viral load – the amount of virus that COVID causes in a person – also differed between adults and young children.
While adults with high viral loads — suggesting they were more contagious — tended to have more severe COVID-19 symptoms, young children didn’t. This suggests that children with mild or no symptoms can still be highly contagious.
Karron says these findings should help parents and others make better decisions. She says that even if young children have no symptoms, they should be tested for COVID-19 if they have been exposed to others with the disease. And she recommends acting on the results.
“If a family is infected with the virus, and the 2-year-old [has no symptoms], and people think about visiting elderly grandparents… you shouldn’t assume the 2-year-old isn’t infected,” says Karron. “That child should be tested along with other family members.”
Testing should also be considered for young children exposed to COVID-19 in childcare facilities, she says.
But other experts didn’t necessarily agree.
“I wonder if that effort is worth it,” says Dean Blumberg, MD, a professor and chief of the Division of Pediatric Infectious Diseases at UC Davis Health in Sacramento, CA.
He notes that recent FDA guidelines for COVID-19 testing require three negative at-home antigen tests — which detect proteins called antigens from the virus that causes COVID-19 — to confirm lack of disease.
“That would take 4 days to get those tests done,” he says. “So it’s a lot of testing. It’s a lot of record keeping, it’s clunky, it’s inconvenient to be tested, and I just wonder if it’s worth the effort.”
Do the findings still apply?
Blumberg also questions whether the study, which was completed nearly a year ago, reflects the current pandemic landscape.
While the experts interviewed had differing opinions on the findings, they shared similar views on vaccination.
“The most important thing parents can do is get their kids vaccinated, get themselves vaccinated, and have everyone in the household vaccinated and up to date on all indicated doses,” Blumberg says.
Karron notes that vaccination will become more important in the coming months.
“Summer is coming to an end; school starts,” she says. “Soon we will be indoors again in large groups. In order to keep young children safe, I think it is very important that they get vaccinated.”