Melbourne: In an unusual case, three kids of COVID-19 positive parents in Melbourne (Australia) have developed antibodies without ever being infected with the coronavirus. 

The article published in the ‘Nature Communications’ journal said that the data indicates that children can mount an immune response to SARS-CoV-2 without virological confirmation of infection, raising the possibility that immunity in children can prevent the establishment of COVID-19 infection.

The authors described clinical features, virology, longitudinal cellular, and cytokine immune profile, SARS-CoV-2-specific serology and salivary antibody responses in a family of two parents with PCR-confirmed symptomatic SARS-CoV-2 infection and their three children, who tested repeatedly COVID-19 negative. 

They added, “Relying on routine virological and serological testing may not identify exposed children, with implications for epidemiological and clinical studies across the life-span.”

The authors said that the cellular immune profiles and cytokine responses of all children were similar to their parents at all timepoints. 

The research was led by Shidan Tosif, Melanie Neeland. David P Burgner and Nigel W Crawford.

Compared to adults, children with severe acute respiratory syndrome coronavirus have predominantly mild or asymptomatic infections, but the underlying immunological differences remain unclear. 

The researchers tracked a family, of which, the parents, mother, 38, and father, 47, attended a 3-hour wedding inter-state without their children, in early March 2020. They returned home 3-days later and developed cough, coryza, and subjective fevers, followed by lethargy and headache that lasted for a period of 14 days. 

Seven days after the onset of the parents’ symptoms, one of the children aged 9 developed a mild cough, coryza, sore throat, abdominal pain, and loose stools, and another child aged 7 developed mild cough and coryza. However, the third child, 5, was asymptomatic. 

As per the researchers, eight days after the onset of the parents’ symptoms, they were notified of an emerging outbreak of SARS-CoV-2 traced to the wedding. The parents were SARS-CoV-2 PCR positive on nasopharyngeal (NP) swabs taken the same day, but repeated NP swabs from the children were COVID-19 negative. 

“Physical distancing precautions were not feasible in the household. The third child had particularly close contact, sleeping in the parents’ bed throughout the period both parents were unwell. All family members recovered fully without requiring medical care,” said the study.

“This in-depth family case study provides novel insights into immunological responses in children exposed to SARS-CoV-2. Despite close contact with infected parents, PCR testing for SARS-CoV-2 was repeatedly negative in all children, who developed minimal or no symptoms,” said the authors.