September 6, 2022 – Don’t count on a runny nose.
Young children with COVID-19 often have no symptoms at all, even if they carry a large amount of the virus, according to a new study.
The researchers found that 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 up to the age of 4 .
This raises concerns that parents, childcare workers and preschoolers may not be seeing the level of infection in apparently healthy young children who have been exposed to COVID-19, wrote lead author Ruth A. Karron, MD, and colleagues in the Journal of the American Medical Association Open.
The study involved 690 individuals from 175 Maryland households who were closely monitored between November 2020 and October 2021. For eight months, they conducted online symptom checks every week and had PCR tests performed that detect the presence of the virus that causes COVID-19 using 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 sampled every week meant we were able to detect these early infections.”
The study is also notable for its focus on young children, Karron said. All households participating in the study had at least one child aged 4 or younger, with 256 of 690 people (37.1%) being in this youngest age group. The other people in the study were 100 children aged 5 to 17 years (14.5%) and 334 adults aged 18 to 74 years (48.4%).
The youngest most likely had no symptoms
By the end of the study, 51 people had tested positive for the coronavirus, including 14 with no symptoms. A closer look showed that children ages 4 and younger who contracted 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 the virus that causes COVID in a person — also differed between adults and young children.
While adults with high viral loads — suggesting they were more contagious — typically had more severe COVID-19 symptoms, this was not the case for young children. This suggests that children with mild or no symptoms could still be highly contagious.
Karron says these results should help parents and others make better decisions. She says young children, even if they don’t have symptoms, should be tested for COVID-19 if they’ve 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 are thinking about visiting elderly grandparents…don’t assume the 2-year-old isn’t infected,” says Karron. “This 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 doubt if it’s worth the effort,” says Dean Blumberg, MD, professor and chief of the Division of Pediatric Infectious Diseases at UC Davis Health in Sacramento, CA.
He notes that recent FDA guidance for COVID-19 testing calls for three negative at-home antigen tests — which detect proteins, called antigens, from the virus that causes COVID-19 — to confirm the absence of disease.
“That would take 4 days to do these tests,” he says. “Well, it’s a lot of testing. It’s a lot of recording, it’s inconvenient, it’s inconvenient to be tested, and I’m just wondering if it’s worth the effort.
Are the findings still valid?
Blumberg also doubts whether the study, which was completed almost a year ago, reflects the current pandemic landscape.
Although the experts interviewed had different opinions on the results, they shared similar views on vaccination.
“The most important thing parents can do is get their children vaccinated, get vaccinated themselves, and get everyone in the household vaccinated and up to date for all doses indicated,” says Blumberg.
Karron notes that vaccinations will become more important in the coming months.
“Summer is ending; School is starting,” she says. “We will be back inside in large groups very soon. To protect young children, I think it is very important that they get vaccinated.”