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Children can test negative for Covid-19 despite having antibodies and mild symptoms


In an Australian family of five, two parents became infected with the coronavirus and passed it on to their three children, but none of them ever tested positive. 

While the adults developed classical symptoms such as a cough, fever and headache, two of the children only had very mild symptoms and the youngest was completely asymptomatic despite sleeping in the same bed as the parents.

However, all five had the same immune response, with antibodies specific for SARS-CoV-2, which causes Covid-19, found in blood and saliva samples of everyone. 

But despite this, none of the children ever tested positive for Covid-19 in PCR throat and nose swabs, seen as the gold-standard for detecting infection.  

Researchers say the case study from the Murdoch Children’s Research Institute (MCRI) in Melbourne indicates children can mount a strong response against the virus once it gets inside their body which prevents it from replicating, limiting its potency. 

Children make up a tiny percentage of coronavirus cases and deaths and researchers are currently trying to find out why youngsters are less susceptible to Covid-19 than adults.  

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In an Australian family of five, two parents became infected with the coronavirus and passed it on to their three children, but none of them ever tested positive (stock)

The researchers found SARS-CoV-2 specific IgA antibodies in saliva of all family members (pictured). IgA is a type of antibody which is secreted into the mouth, nose, lungs and gut

The parents, a 38-year-old mother and a 47-year-old father, caught the virus at a wedding in March the early days of the pandemic and developed symptoms including a cough, congested nose, fever and headache.

Lethargy and headaches persisted for 14 and 11 days for the mother and father, respectively.  

Although the parents were infected, the children were still in very close contact with their mum and dad because it was not known the event hosted a positive individual until a week after the parents returned home. It was only at this point the parents were tested and found to be Covid-positive. 

In March, there was no understanding of the risk coronavirus posed, no widespread mask-wearing and no social distancing.   

Seven days after the onset of the parents’ symptoms, child one (a nine-year-old boy)  developed a mild cough, sore throat, abdominal pain and loose stools.

The middle child, a seven-year-old boy, developed mild cough and coryza, a runny nose.

The youngest, a five-year-old girl, had no symptoms.  

Pictured, a timeline of events for the Australian family of five and their brush with coronavirus following the infection of the two parents at a wedding in March 

The children repeatedly tested negative for COVID-19 and displayed either no or very minor symptoms.  

Medics took samples of blood and saliva from all five family members (two parents and three children) as well as nose and throat swabs every two to three days. 

The researchers found SARS-CoV-2 specific IgA antibodies in saliva of all family members. IgA is a specific type of antibody which is secreted into the mouth, nose, lungs and gut. 

‘Despite close contact with infected parents, PCR testing for SARS-CoV-2 was repeatedly negative in all children, who developed minimal or no symptoms,’ the researchers write in their study, published in the journal Nature Communications.

‘However, the children had similar cellular and SARS-CoV-2 specific antibody-mediated immune responses to their parents, suggesting that the children were infected with SARS-CoV-2 but, unlike the adults, mounted an immune response that was highly effective in restricting virus replication.’  

Scientists analysed the samples in a laboratory to decipher what type of immune response the children had and how it compared to their parents. 

Dr Melanie Neeland, who led the laboratory-based aspect of the report, said: ‘The youngest child, who showed no symptoms at all, had the strongest antibody response.’

But the children had the same level of cytokine response as their parents. 

Cytokines are key chemicals in the fight against coronavirus infection. They are involved with fighting disease but they can spiral out of control, going haywire and worsening a patient’s condition by attacking their own cells. 

‘The discordance between the virological PCR results and clinical serological testing, despite an evident immune response, highlights limitations to the sensitivity of nasopharyngeal PCR and current diagnostic serology in children,’ the researchers add. 

Common cold could give children immunity to the rare MIS-C hyper-inflammatory condition caused by the coronavirus, study suggests 

Children who have previously caught the common cold have coronavirus antibodies that prevent them from developing the hyper-inflammatory condition called MIS-C, new research suggests.  

The rare disease is caused by infection with the SARS-CoV-2 coronavirus, the same pathogen responsible for the current COVID-19 pandemic. 

Research has found the condition, known as multisystem inflammatory syndrome in children (MIS-C), is different to both COVID-19 and Kawasaki disease. 

However, little is known about why some children, roughly a month after being infected with the coronavirus, develop MIS-C symptoms. 

Indicators of the disease include a rash, fever and abdominal pain as well as conjunctivitis, a cough and a headache. 

Experts at the Karolinska Institutet in Sweden compared healthy children with youngsters suffering from MIS-C and Kawasaki disease.  

Blood tests of 13 MIS-C-patients, 28 Kawasaki disease patients and uninfected children revealed the MIS-C cohort lack antibodies against the common cold. 

Researchers say it is possible antibodies obtained after infection with the common cold could play a role in controlling the development of MIS-C.   

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