It is a nightmare repeatedly playing in parents’ minds: Their child is welcomed back to their classroom, but in the excitement the kids get too close to one another, sharing germs.

The children may not have coronavirus symptoms or be able to express that they are not feeling well, unwittingly spreading the virus as they continue to go to school or come into contact with adults.

Only when the older members of the family — those more likely to show signs of infection — get tested do they learn what has happened: It’s covid-19, and by then it’s everywhere.

As preschools, elementary schools and day cares welcome returning children nationwide this fall, researchers are hoping to learn more about the transmission of the coronavirus among younger children. But efforts to screen kids may be hindered by several factors: age limits at certain testing sites; fear of or discomfort from swab testing; and the tendency for children to not exhibit signs of infection, making them less likely to qualify for immediate testing.

“I think it’s problematic not knowing,” Charles Schleien, chairman of pediatrics at Cohen Children’s Medical Center at Northwell Health in New York, said about limits on testing access for children. “I think parents will have to be incredibly vigilant about any symptoms and keep the kid home and assume the worst.”

Washington Post reporter Chelsea Janes details the possible role that children play in spreading coronavirus and how this impacts school reopenings. (The Washington Post)

A patchwork of age limits at testing sites may make it difficult for parents to find a dependable location for speedily checking on their sick child, pediatric health and testing experts told The Washington Post, especially as the rules of testing have evolved with invention and capacity.

CVS announced Sept. 11 that it would lower its age limit from 16 to 12 at more than 2,000 drive-through testing sites. The pharmacy giant’s minimum age is set by clinical experts because of the viability of self-swab tests done by children younger than 12, according to company spokesman Joe Goode.

Walgreens’ age limit is 18 at its pharmacy testing sites. The company did not respond to requests for comment from The Washington Post about why it does not test children.

Pediatricians and hospitals can order tests without age limits. Some sites, such as the county-run locations in San Diego, recommend a hospital or alternative location for children.

The county doesn’t permit testing of those younger than 11 at its testing sites but has a partnership with a hospital to run pediatric testing, said county spokeswoman Sarah Sweeney, who cited a state law regarding consent as to why younger children cannot be tested at sites.

Fewer than one-quarter of the state-supported testing sites in Florida allow all ages to be tested. Ahead of the first day of reopened schools, Florida announced in August that it would prioritize pediatric testing at sites that have it.

Barriers to testing, according to the American Academy of Pediatrics, limit our understanding of how the virus spreads.

“It would be helpful for pediatricians to identify resources to learn how to obtain tests on children of all ages or else refer those patients to centers where they can be tested,” said Yvonne “Bonnie” Maldonado, a pediatrics and epidemiology professor at Stanford University School of Medicine and chair of AAP’s infectious diseases committee. “This would improve our ability to identify infection in infants and children of all ages.”

For rural schools in Arizona, reopening campuses to provide essential services could mean bringing back hundreds of kids. Superintendents say they aren't ready. (The Washington Post)

Public health experts already have cautioned that isolation is one of the most effective ways to prevent spread among children. Yet with children once again gathering in schools and child-care centers after a summer reprieve, clusters have begun emerging — as well as cases where the virus spread from youngsters to adults.

An outbreak among a dozen children at two Salt Lake City day-care facilities exposed family members, sickening 12 and hospitalizing one parent, according to a Centers for Disease Control and Prevention report released Sept. 11. Only three of those children showed any symptoms.

Ahead of the semester, in August, the CDC made a controversial change to its testing recommendations, saying the screening of asymptomatic people is unnecessary. The CDC also does not recommend universal screening in schools.

Bypassing asymptomatic carriers for testing could allow the virus to fester in communities unchecked, researchers have found.

Coronavirus screening conducted in 20 South Korean hospitals and two isolation facilities did not identify coronavirus symptoms in most children younger than 19, according to a non-peer-reviewed paper published Aug. 28 in JAMA Network, implying that the “inapparent infections in children may have been associated with silent COVID-19 transmission in the community.”

“A surveillance strategy that tests only symptomatic children will fail to identify children who are silently shedding virus while moving about their community and schools,” the authors said. “In regions where use of face masks is not widely accepted or used by the general public, asymptomatic carriers may serve as an important reservoir that may facilitate silent spread through a community.”

However, other research has indicated that pediatric patients do not shed as much of the virus as infected adults. A small study published in the Pediatrics medical journal in July found that of 74 pediatric patients in China, there was no evidence that the virus was transmitted from children to adults. But schools were closed at the time of the review.

Surveillance testing of children in most schools is neither feasible nor worth the effort, said George Rutherford, a pediatrician and epidemiology professor at the University of California at San Francisco. For more worthy targets for screening efforts, Rutherford pointed to farmworkers and other groups lacking health-care access who are also most vulnerable to the most severe symptoms of the disease caused by the virus.

Eyebrow-raising case counts have been documented among older students, including on college campuses, Rutherford said.

“High schools and middle schools are Petri dishes of infection, and we know that already,” Rutherford said. “And there’s no difference between high schools and colleges — except alcohol.”

Outbreaks in K-12 schools may not garner as many national headlines, as reporting varies by state. Led by teachers, one national effort to track infections in schools has counted more than 11,700 cases in 3,122 schools, according to the National Education Association’s dashboard of infections publicly reported since mid-July.

Screening strategies suggested by Duke University’s Margolis Center for Health Policy in a report released Sept. 9 recommend testing all students and teachers in schools every two weeks if cases exceed one per 100,000 people in the area.

But the nation’s capacity for testing may not be able to handle that, especially amid a surge in infections.

Mass screening for students may also not be effective because children, energetic and social, can pick up the virus after being swabbed, and the infection would not be detected, said Christine McKiernan, director of pediatric critical care at Baystate Medical Center in Massachusetts.

“It cannot tell you if I test you on Monday and you go and catch it somewhere Tuesday, and then Friday you’re in school,” McKiernan said. “The testing is just a point of time.”

It is not possible to test people as much as you would like to test them, said Kristin Moffitt, a pediatrics professor at Harvard Medical School.

“From a broad-strokes perspective, it makes the most sense in any setting to prioritize testing for symptomatic people if they have been around other people, such as settings like a classroom,” Moffitt said, adding that it’s also important to test those who are at the greatest risk of severe symptoms.

Testing kids is also no easy task: The business end of a nasopharyngeal swab is an uncomfortable sight for anyone, let alone a sick child new to medicine, pediatricians said.

“Even what we consider minor things like vaccinations and blood screenings can be traumatic for children,” Kim Stephens, president of the Association of Child Life Professionals said, “and that have long-term harm and impact people’s ability to seek health care as adults.”

Child life specialists help kids adjust to medical settings, and especially during these times, are normalizing and explaining the pandemic in “child-friendly terms” during hospital visits, Stephens said.

Stephens said teaching parents and children about testing is going to continue to be vital indefinitely.

“This is obviously not something that’s going to go away,” Stephens said. “Short of getting a vaccine within a year, kids are going to be tested on a regular basis as schools reopen. Helping parents have tools to prepare their child is going to be really important.”