Children can study coronovirus at a high level


In the national conversation about the reopening of schools, this has been a comforting prohibition: young children are mostly spared by coronoviruses and do not seem to spread it to others, at least not very often.

But on Thursday, a study introduced an unwanted wrinkle in this spontaneous narrative.

According to research, the nose and throat of infected children have at least as many coronoviruses as infected adults. In fact, children under 5 can host 100 times as much of the virus in the upper respiratory tract as adults, the authors found.

This measurement does not necessarily prove that children are giving the virus to others. Nevertheless, the findings should influence the debate over the reopening of schools, many experts said.

“The school’s situation is so complex – there are many nuances beyond just the scientific one,” Dr. Taylor Heald-Sergeant, Ann and Robert H. of Chicago A pediatric infectious disease specialist at Lurie Children’s Hospital, who led the study. Published in JAMA Pediatrics.

“But one way out of this is that we cannot assume that children are not sick, or very ill, because they do not have the virus.”

The study is not without Kewitt: it was small, and did not specify participants’ race or sex, or whether they had underlying conditions. The tests looked for viral RNAs themselves, rather than genetic fragments of coronoviruses themselves. (Its genetic material is RNA, not DNA.)

Nevertheless, experts were anxious to learn that young children may take significant amounts of coronavirus.

“I have heard many people say, ‘Well children are not susceptible, children are not infected.” And it clearly shows that this is not true, ”said Stacey Schulz-Cherry, a virologist at St. Jude Children’s Research Hospital.

“I think this is an important, really important, first step in understanding the role that children are playing in transmission.”

Jason Kindrachuk, a virologist at the University of Manitoba, said: “Now that we are moving around at the end of July and trying to open schools next month, it really needs to be considered.”

The standard diagnostic test increases the genetic material of the virus in a cycle, with the signal intensifying every round. Initially, the more viruses the swab contains, the fewer cycles are needed for a clear result.

Dr. Heidel-Sergeant, who has a research interest in coronaviruses, began to see that children’s trials were coming up with lower “cycle thresholds” or CT, suggesting that their samples were with the virus.

Questioned, he called the hospital’s lab on Sunday and asked him to look at the test results for the past several weeks. He said, “It wasn’t even something we saw.”

He and his colleagues analyzed samples collected at the drive-through testing sites in Chicago and between April 23 and April 27 with nasopharyngeal swab, which showed symptoms of Kovid-19 among those who came to the hospital for any reason. .

He saw the swab taken from 145 people: 46 children under 5; 51 children between 5 and 17 years of age; And 48 adults between 48 and 18 years of age. Really sick children would be expected to be very critical of the virus, the team excluded children who needed oxygen support. Most children in the study reported only fever or cough, Drs. Said Heald-Sergeant.

To compare the groups objectively, the team consisted of only children and adults who had mild to moderate symptoms and for whom they were aware of the symptoms. Dr. The Heald-Sergeant excluded people who did not have symptoms and did not remember when they began to become ill, as well as those who had symptoms for more than a week before the test.

The results were confirmed by Dr. Heal-Sergeant Humps: Older children and adults had similar CTs, with an average of about 11 and up to 17 years of age. But children below 5 years had a low CT of about 6.5. The upper limit of the range in these children was a whistle of 12, though – compared to still older children and adults.

“This certainly suggests that virus levels in children are similar and probably even higher than in adults,” Dr. Heidel-Sargeant said. “It wouldn’t be surprising if they were able to shed the virus” and spread it to others.

The results are consistent with those from a German study of 47 infected children between 1 and 11 years of age, which showed that children who did not have symptoms had higher viral load than adults’. And a recent study in France found that asymptomatic children had similar CT values ​​as children with symptoms.

Dr. Kindrachuk, who relied on this metric during the Ebola outbreak in West Africa, said the CT value is a reasonable proxy for the amount of coronovirus.

Nevertheless, he and others stated that ideally researchers would develop infectious viruses from samples instead of testing them for RNA of the virus.

“I suspect that this would probably translate into a sense that there is more real virus out there, but we can’t say that without looking at the data,” said Juliet Morrison, a virologist at the University of California, Riverside.

Some RNA viruses multiply quickly and suffer from genetic errors that render the virus infecting cells inefficient. Some RNAs found in children may represent these “defective” viruses: “We need to understand how infectious the virus really is,” Dr. Shultes-Cherry said.

(Researchers say they do not have access to the type of high-security laboratory needed to develop the infectious coronavirus, but other teams have cultivated the virus from children’s samples.)

Experts all emphasize that the findings at least indicate that children may be infected. People who disturb a lot of the virus can spread it to teachers and other staff members of the school when they reopen it in their homes, or in schools.

Many school districts plan to protect students and staff members by implementing physical disturbances, cloth coverings, and hand hygiene. But it is unclear how staff members and teachers can prevent young children from getting too close to others, Dr. Kindrachuk said.

“Frankly, I just haven’t discussed much about how that aspect can be handled,” he said.

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Observations from schools in several countries have suggested that, at least in places with mild outbreaks and with preventive measures, children do not spread coronovirus efficiently to others.

Strong immune responses in children can limit both how many viruses they can spread to others and for how long. Children’s overall health, underlying conditions such as obesity or diabetes, and sex can also affect their ability to transmit the virus.

Some experts have suggested that children may transmit fewer viruses due to their small lung capacity, height, or other physiological aspects.

Dr. Morrison rejected those suggestions. The virus is shed from the upper respiratory tract, not the lungs, he noted.

“We’re going to reopen day care and primary schools,” she said. If these results hold up, “then yes, I would worry.”

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