COVID-19 test imperfect in children, raising questions about detecting it at school, doctor says

A Toronto pediatrician says COVID-19 tests may not be sensitive enough to always accurately detect the virus in children, raising questions about containing the novel coronavirus when students return to school next month.

Dr. Dina Kulik, the director of Kidcrew, a pediatric clinic in the city, says since the start of the pandemic she's seen children with COVID-19 displaying an array of symptoms, from diarrhea to rashes.

But some children who were exposed to the virus, and had the same symptoms, came up negative on the naso-pharyngeal swab test — a procedure where a swab is inserted deep in the nasal cavity to collect a sample.

"I've had many patients whose parents or family members had confirmed COVID," said Kulik. "Their children had symptoms and yet their tests came back negative. The only explanation for that is the test is imperfect." 

The test's accuracy is a concern for Kulik as the school year is about to start. She worries that public health officials may rely too heavily on negative COVID-19 tests results to allow sick students to return to school. 

Swab test can be '90-95%' accurate, doctor says 

Some infectious disease specialists say getting a proper nasal swab sample from a child may be challenging and could lead to error.

Another issue, says clinical scientist Dr. Allison McGeer, is at what stage in the infection a child is tested. 

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"The nasopharyngeal swab test is probably on the order of 90-95 per cent if you are shedding virus at that time. If you got exposed a week ago and you just developed symptoms, you might not be shedding enough virus for it to be detectable for a couple of days," McGeer told CBC Toronto. 

Dr. Gary Kobinger, the director of the infectious disease research centre at the University of Laval, agrees that when a patient is tested plays a huge role in determining how much of the virus they're displaying and how infectious they are. 

But, since the virus is still new, he doesn't rule out the possibility of false negatives in children. 

When it comes to schools, he says, Canada is entering "a bit of unknown territory."

Ontario releases COVID guidebook for schools

On Wednesday the Ontario government released operational guidelines for how schools will manage COVID-19 outbreaks along with any illnesses in general. 

The 21-page document explains that if a child is sick with COVID-19 symptoms, parents or guardians should "seek medical advice, including the recommendation of testing for COVID-19 as appropriate or as advised by their medical provider."

However, Ontario's Chief Medical Officer of Health Dr. David Williams clarified at a news conference Tuesday that it is up to parents to decide whether their children will be tested for the novel coronavirus. 

Both Ontario's Ministry of Health and Toronto Public Health say they were unaware of consistent false negatives in children. However, the spokesperson for Toronto Public Health, Dr. Christine Navarro, called "testing a complex area." 

In an email to CBC Toronto, she added that "COVID-19 is still a new virus and the science continues to unfold, it is not unexpected that testing continues to be refined for this virus."  

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One of the reasons the province is leaving it up to parents and the family doctors to decide whether a child needs to be swabbed for COVID-19 is because children get sick easily in school settings, contracting a host of different viruses. 

Some COVID-19 symptoms Kulik and other doctors have seen in children are: 

• Roseola, a viral illness with high fever and a distinctive rash just as the fever breaks.
• Diarrhea.
• Vomiting.
• High fever.

Ontario's back-to-school document states that if a child's COVID-19 test comes back negative, they should wait 24 hours after their symptoms subside to return to school. 

For Kulik, that's too short a timeframe. She believes children who display any COVID-19 symptoms, regardless of their test results, should have a mandatory two-week quarantine.

"If you have any viral symptoms … I do believe you should be avoiding people for 14 days," she said.

"I'm certain that we're going to find out one day that these symptoms are COVID, even though these kids have swabbed negative."