Until now, scientists have not yet been able to explain why children seem less likely to contract the SARS-CoV-2 virus. However, a study conducted by a team of researchers on an Australian family may well shed more light on this mystery.
According to information shared, in this family from Australia, the parents contracted SARS-CoV-2 after attending a wedding and then exhibited symptoms of COVID-19. The whole family then had two tests to confirm coronavirus infection.
Oddly enough, the tests came back positive for the parents, but negative for two of the children, despite the fact that they presented mild symptoms of disease. More surprisingly, the third, the youngest of them presented no symptoms throughout the episode, even if the members of this family could not respect the precautions of physical distance customary during their quarantine.
This led researchers to take an interest in their cases.
The details of this study which ultimately explains things
To perform the tests, the researchers took and analyzed twice over three days samples of blood, saliva, stool and urine as well as swabs from the subjects’ noses and throats. Repeated polymerase chain reaction tests (PCR test) with SARS-CoV-2 have always been negative.
However, specific antibodies to the virus have been found in the saliva of all family members and during detailed serological tests. This means that once exposed to the virus, these children’s immune systems reacted by developing antibodies capable of countering the infection without testing positive for the virus. The youngest who was asymptomatic seemed from elsewhere having developed the strongest immune response.
In addition, the researchers found that plasma levels of cytokines, the molecular messengers responsible for the inflammatory response, remained weak. This explains the fact that these children presented mild symptoms or even absent of the disease, according to scientists.
Proof that children are resistant to SARS-CoV-2
According to this study, children who have been infected with the virus have developed a very effective antiviral reaction capable of limiting the replication of the virus, and even of reducing the viral load to a level undetectable by PCR.
Which means that at some level, children’s immune systems are able to respond to and deal with the virus effectively, which keeps them from getting seriously ill.
In addition, the discrepancy observed between the virological results of PCR and clinical serological tests reveals that there is a certain limit as to the sensitivity of nasopharyngeal PCR (the famous nasal swab swabs) and the diagnostic serology currently used, for children.
The conclusions of this research were published in Nature Communications.