Scientists at the University of Melbourne in Australia have recorded an abnormal case of coronavirus infection in children whose PCR test results for SARS-CoV-2 were negative all the time. At the same time, the infected showed specific antibodies to the virus. This is reported in an article published in the journal Nature Communications.
The researchers monitored the health of a family of five in which both parents contracted COVID-19. Symptoms began a few days after they returned from a trip they had not taken with them. Signs of illness included cough, nasal congestion, fever, and headache. After going to the doctor, the whole family was tested for SARS-CoV-2, while the test results were positive for the parents and negative for the children, despite the fact that they had been in contact with loved ones for a week and a half.
Although two boys, ages nine and seven, subsequently developed mild symptoms, repeat tests were still negative. The five-year-old daughter was completely asymptomatic, although she often slept in the same bed with her parents during their illness.
The researchers asked the family to take part in a study in which they took samples of blood, saliva, stool and urine from everyone, as well as swabs from the nose and throat every two to three days. It turned out that each family member had antibodies against SARS-CoV-2 in the saliva. Thus, a certain level of exposure from the coronavirus triggered an immune response in children, with the youngest child in the family having the highest antibody response.
“The fact that the children were able to fight off the virus and didn’t even have a positive test result suggests that their immune systems are active enough to respond and effectively fight the virus. However, they never get sick with COVID-19,”says study author Shidan Tosif.