Since the early days of the coronavirus epidemic, scientists have observed that children appear to be less susceptible to developing COVID-19, although the exact causes are unclear.
Now, an unusual case in Australia can give a unique understanding of the mystery, thanks to the experience of a young family in Melbourne.
In this family of five, both parents became ill with COVID-19 after attending an interstate wedding without their children. However, the symptoms did not appear until the days after they returned from the trip.
Though completely unaware of them, they brought SARS-Cove-2 to their home, and exposed their children to it.
Family with MCRI researchers. (MCRI)
Once both parents developed symptoms, including cough, congestion, runny nose, fever and headache – the whole family was tested for the virus. Parental tests came back positive. The children’s tests came back negative.
“It was a surprise to leave the jaws because they spent two weeks with us when they were covid-positive,” mother Lila Savenko told ABC News.
Still, the really surprising part was yet to come.
Healthcare staff asked the family to repeat, but again the children’s tests came back negative for SARS-CV-2, even though the two boys in the family (9 and 7 years old) were in mild symptoms.
The youngest child, a 5-year-old daughter, remained unresponsive throughout the episode, although she often slept in the same bed as her parents during her illness (physical distance vigilance may not be possible at home during their quarantine).
Surrounded by the children’s negative results while living close to their infected parents, the researchers analyzed their blood, saliva, stool and urine samples, and asked them to take part in one of the two studies taking nose and throat scars. Three days.
Surprisingly, despite giving children frequent polymerase chain reaction (PCR) tests, the children were consistently SARS-Cowi-2 PCR negative, the researchers found the CARS-Cowi-2 specific antibodies in the saliva of all family members, and in detailed serology tests.
In other words, children have never tested positive for the virus, but exposure to the virus stimulated their inner immunity at some level, and seemed able to cope with an infection.
“The youngest child, who showed no symptoms, had a strong antibody response,” says Melanie Nieland, an immunologist at the Murdoch Children’s Research Institute (MCRI).
“Despite the response of active immune cells in all children, the levels of cytokines, molecular messages in the blood that could stimulate the inflammatory response, remained low. These were consistent with their mild or no symptoms.”
Fortunately, all the family members who were sick recovered and did not need medical care.
The mechanisms behind the immune response of children are not yet fully understood, but finding out how and why their immune responses became active (in the absence of any confirmed cases of the virus) may shed more light on children’s susceptibility to COVID-19 more widely.
“This study is our first step in really looking at children’s immune systems and what components they may be reacting to due to the virus,” said Shidan Tosif, a pediatrician at the University of Melbourne, the study’s first author. Age.
“The fact that these children were able to stop the virus and even without showing positive test results indicates that they have some level of their immune system capable of reacting to the virus and dealing effectively, without ever becoming too upset. “
Effectively, the researchers believe that children were actually infected with the virus, but their immune system was somehow able to mount an anti-virus response that was as effective in preventing virus replication as their parents.
That immune response was so effective, it could have brought the viral load so low that it went under the sensitivity of the PCR test, which is the issue that further examination gives, the team thinks.
“The contrast between virological PCR results and clinical serological testing highlights the susceptibility of nasopharyngeal PCR in children and the limitations of current diagnostic serology, despite the obvious immune response,” the researchers write.
For Lila Savenko and her family, they are just happy to have all the swabs and tests behind them, and thrilled for our better understanding of this wider virus, and for contributing in their own way to what it stimulates within us.
“It was a ‘wow’ moment that even though the kids tested negative, they developed antibodies,” Svenko said ABC News.
“You could only see the look on the doctors’ faces. They were absolutely amazed and excited to think that this discovery was indeed made.”
These findings are reported Nature Communications.
.
