Children might be more vulnerable to Covid-19 than once believed, with new research suggesting that they are able to contract and spread the virus, especially if they don’t take precautions such as wearing a mask.
Several studies and reports published in recent weeks found coronavirus infections among children of all ages at places ranging from schools to camps to homes. Other research suggested that kids, especially older ones, can be a driving force behind transmission.
And some researchers found children carry high levels of Covid-19’s genetic material in their upper respiratory tract, which doesn’t mean they are transmitting the virus but that they potentially could. Most of the studies have limitations, and more research is needed, experts say. Yet the new studies, together with reports of outbreaks among children at some schools overseas and a summer camp in Georgia, have persuaded many researchers that children aren’t as immune to Covid-19 as initially thought.
“Are they susceptible to catching the virus? Absolutely. Are they able to transmit the virus? Absolutely,” said Joelle Simpson, interim chief of emergency medicine at Children’s National Hospital in Washington, D.C.
In the U.S., 45 children under the age of 15 years have died from Covid-19, compared with nearly 25,000 deaths of people between the ages of 45 to 64, according to the latest data from the U.S. Centers for Disease Control and Prevention. Its data also show far lower rates of hospitalization among children. Meanwhile, other studies, including one published in June in the journal Pediatrics, found infected children under 18 years old in China tend to exhibit only mild or moderate symptoms, or no symptoms at all. Yet the latest research indicates children may be carriers just as much as adults.
Even when experiencing only a mild or moderate case, children under the age of five might have anywhere between 10 to 100 times as much of Covid-19’s genetic material, viral RNA, in their upper respiratory tracts as older children and adults, according to a study published last month in the journal JAMA Pediatrics. The study didn’t show children were able to transmit the virus. Yet researchers say the findings suggest children are likely capable of spreading the coronavirus. The change in thinking comes as schools prepare to begin a new year, including some still deciding whether it would be safe for children to return to classrooms. President Trump and some members of his administration have urged schools to reopen.
Some schools in the U.S. can likely safely reopen, researchers say, but the new findings suggest the facilities should proceed carefully. And, they added, schools should wait until community transmission is under control. They also should take steps that can reduce the risks for students and staff, such as widespread masking and frequent cleaning, along with social distancing and good ventilation, experts recommend. A number of schools overseas have reopened with little incident after taking stringent precautionary steps. Without such actions, researchers warn, schools reopening in the U.S. could experience outbreaks like those that hit facilities in Isra and France. “Our schools are little mini microcosms of our cities that they’re in—what’s happening in cities is what’s going to happen in schools,” said Tina Hartert, a professor of medicine at the Vanderbilt University School of Medicine, who is leading a study, funded by the National Institute of Allergy and Infectious Diseases, exploring the infection rate in children and people they live with across nearly 2,000 households in the U.S. “Until there is definitive data one way or the other, we have reason to believe from decades of data from other respiratory viruses that children are very good transmitters,” Dr. Hartert said. “There isn’t a lot of reason to believe that that wouldn’t be the case with this virus.” Several factors contributed to the initial thinking that children were less affected by Covid-19. The virus might not have spread among many children during the early months, in part because schools were closed, playgrounds were locked up and kids were at home. In addition, Covid-19 cases in children appear to become serious less frequently than in adults. “Our estimates of [how kids] spread the virus may have been a bit inaccurate earlier on,” Children’s National Hospital’s Dr. Simpson said. “And as certain states have loosened restrictions and kids have been able to congregate, it’s showing that it does spread, and we do have to factor in the prevalence of the virus in the pediatric population.” She and a team of researchers published a study this month in the journal Pediatrics finding a nearly 21% positive Covid-19 test rate among 1,000 children and young adults with mild symptoms who were tested at an exclusively pediatric testing site this spring. Other reports and studies point to children as transmitters. At the overnight summer camp in Georgia, 260, or 76%, of campers, staff members and trainees whose test results were available were infected by Covid-19 shortly after arriving in June, according to a report released recently by the CDC. Most of the cases, 231, were in people age 17 or younger. The camp required all attendees to provide documentation of a negative Covid-19 test no more than 12 days before arriving, and staff were required to wear cloth masks, the report said. Yet campers weren’t required to wear masks, and windows and doors weren’t opened for increased ventilation. Campers also participated in daily vigorous singing and cheering. Researchers warned against reading too much into a single, anecdotal case. An overnight camp where children share cabins isn’t the same as a school, the researchers said, and several U.S. day cares, camps and summer schools stayed open this summer without incident.
In a study out of South Korea, researchers attempted to trace the contacts of roughly 5,700 people, including about 150 kids ages 19 and younger, who had the first identified or documented cases of Covid-19. The researchers found that children between 10 and 19 years old transmitted the virus within their own households at the same rate as adults of certain ages. Children under the age of 10 didn’t spread the virus as much, according to the study, which the journal Emerging Infectious Diseases posted last month. The findings might have been skewed by a small number of children and their contacts in the study, and it might have missed asymptomatic cases, researchers said. “My take-home point from all of these studies is that I think there is a continuum—I don’t think children biologically change dramatically at age 10,” said William Raszka, a professor of pediatrics at the Larner College of Medicine at the University of Vermont. “I think that the older [kids] are, the more likely it is that [they] are going to act like an adult and transmit like an adult.” Researchers who examined an outbreak in an Israeli school for older children shortly after it reopened in May said two known coronavirus cases ultimately led to 153 students and 25 staff members—13.2% and 16.6%, respectively—testing positive for the virus. And the virus spread outside the school, to 87 close contacts. Many who were infected didn’t report symptoms, the researchers said in an article published in July in the European scientific journal Eurosurveillance. The virus’s spread might also have been exacerbated by crowded classrooms, as well as a heat wave that prompted continuous use of air-conditioning and a three-day exemption from face masks for children.