Three children in Australia developed coronavirus antibodies despite testing negative for the virus multiple times and, having mild to no symptoms.
Research has shown that a majority of children suffer from an asymptomatic or mild infection when exposed to SARS-CoV-2. However, it is unclear as to why children mount a different immunological response than adults. A recent case in Australia has provided doctors with further insight into understanding the immune response to COVID-19 in children. According to the study published in the journal Nature Communications, three children ended up with coronavirus antibodies despite testing negative for the virus multiple times.
It was jaw-droppingly amazing because they’d spent a week and a half with us while we were COVID-positive.
Leila Sawenko, mother
All 3 Siblings Test Negative on Multiple Tests
A week after returning from a wedding, parents Leila Sawenko and Tony Maguire started experiencing headaches, fever, and a cough. None of their 3 children had accompanied them to the wedding. However, soon two of their children started exhibiting similar symptoms while the youngest remained asymptomatic.
Credit: Murdoch Children’s Research Institute (MCRI)
When news reached them of a COVID-19 outbreak liked to the wedding, they decided to get the whole family tested. PCR (polymerase chain reaction) testing of the nasopharyngeal swabs confirmed the presence of SARS-CoV-2 in the parents.
However, all three children tested negative despite having constant, close contact with their parents. Thinking it was a false negative, doctors repeated the tests in all three children, sending it to two different labs. Much to their amazement, the results came back negative each time.
This is one of the first reports to actually show an immune response in children who have been exposed to the virus in their household
Dr. Melanie Neeland, Murdoch Children’s Research Institute
Coronavirus Antibodies Found in all Three Siblings
In hopes to study this mystery further, researchers at Melbourne’s Royal Children’s Hospital and the Murdoch Children’s Research Institute (MCRI) asked the family to be a part of a study. They collected blood, saliva, stool, and urine samples from all family members.
Although the children tested negative for SARS-CoV-2, doctors found COVID-19 antibodies in all three. The youngest child showed the strongest antibody response despite being asymptomatic and being the most in contact with the parents.
Despite the active immune cell response in all children, levels of cytokines, molecular messengers in the blood that can trigger an inflammatory reaction, remained low. This was consistent with their mild or no symptoms.
Dr. Melanie Neeland, Murdoch Children’s Research Institute
The researchers plan to monitor the family’s immune response at 6 and 12 months.
The Mysterious Immune Response
The findings of the study suggest that the children did get infected by the virus, however, their immune response was highly effective in restricting viral replication. This could have brought the viral load down to levels undetectable by PCR testing. The researchers, therefore, believe that the current nasal and oral swabs are not sensitive for detecting the viral response in children.
Further testing on larger samples is required to establish an understanding of the immune response in children.
Reference:
Tosif, S., Neeland, M.R., Sutton, P. et al. Immune responses to SARS-CoV-2 in three children of parents with symptomatic COVID-19. Nat Commun 11, 5703 (2020). https://doi.org/10.1038/s41467-020-19545-8
He, J., Guo, Y., Mao, R., & Zhang, J. (2020). Proportion of asymptomatic coronavirus disease 2019: A systematic review and meta-analysis. Journal of medical virology, 10.1002/jmv.26326. Advance online publication. https://doi.org/10.1002/jmv.26326
