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  • A new study has cast doubt on rapid tests being as effective at detecting COVID-19 in children as in adults.
  • According to researchers, the accuracy of the rapid antigen tests is already “highly variable” in adults, and frequently much lower than claimed by manufacturers.
  • The findings indicated that among asymptomatic children, diagnostic sensitivity was about 56 percent.

While we rely on lateral flow tests (LFT) to know when to isolate from others, recent research published in the journal BMJ Evidence-Based Medicine suggests these tests may not perform as well in children.

According to researchers, the accuracy of LFTs, also called rapid antigen tests, is already “highly variable” in adults and frequently much lower than claimed by manufacturers.

Researchers analyzed research databases and preprint servers for studies published between 2020 and May 2021 that compared the accuracy of lateral flow antigen tests with PCR tests (considered the gold standard) in children.

They found 17 relevant studies that involved 6,355 children and 8 antigen tests from 6 brands.

Data from these studies were combined to determine their diagnostic sensitivity and specificity.

Sensitivity was defined as how well a test detected disease or infection, while specificity was how well a test identified people who had not contracted the virus.

According to the findings, the overall sensitivity of the evaluated tests was about only 64 percent.

Researchers then restricted their analyses to children with symptoms and without.

They found that in symptomatic children, LFTs detected infection at about 72 percent of cases, based on 3,413 children in 13 studies.

“Sensitivity estimates of antigen tests varied broadly among studies and were substantially lower than reported by manufacturers,” the study authors wrote.

“With symptoms, the sensitivity rose a little bit to 72 percent and again, the specificity if the test was positive was pretty good at 99 percent,” Dr. Robert G. Lahita, director of the Institute for Autoimmune and Rheumatic Disease at Saint Joseph’s Health and author of “Immunity Strong,” told Healthline.

They noted that the intended use of most tests is for symptomatic people, so performance data reported by manufacturers typically refer only to those with symptoms.

The findings indicated that diagnostic sensitivity was just over 56 percent among asymptomatic children, based on 2,439 children in 10 studies.

Lahita explained that the intended use of most tests is limited to people with symptoms and emphasized, “Why get a test if you have no symptoms?”

“Because even if you get the test, you’re not sure that you do or don’t have the disease,” he said. “Before you have symptoms, like the day or two before, that’s when you’re the most infectious, and that’s when you can really pass the disease off on to other people.”

“Taking into account test-specific pooled results, no test included in this review fully satisfied the minimum performance requirements as recommended by WHO…, the US [Food and Drug Administration],” concluded researchers. “Or the Medicines and Healthcare products Regulatory Agency (MHRA) in the UK.”

According to the study authors, while LFTs complement PCR tests, extend test capacity, and are invaluable when rapid results are essential, they come at the price of lower diagnostic accuracy.

“Most notably a lower diagnostic sensitivity, which increases the risk of missing cases, including those with pre-symptomatic infection who have yet to enter the most infectious period,” they wrote.

Dr. Adrianna Bravo, FAAP, pediatrician and senior medical adviser for Inspire Diagnostics, which provides rapid testing, acknowledged that the rapid tests aren’t perfect but said they’re still an important tool to keep kids in school.

She emphasized that the inaccuracy of the tests has been known since the tests were given emergency authorization, but they serve an essential role.

Bravo explained that while the tests won’t catch every single case, school mask mandates can still prevent transmission from any false negatives.

She added that the LFTs are one way to prevent the harmful effects of repeated school closings on children’s psychological health.

Dr. Tanya Altmann of Calabasas Wellness Center in Calabasas, California, said the findings of this study wouldn’t change her approach to the pandemic.

“I think it is interesting but doesn’t really change my school health plans in the schools I advise across the country,” she said. “What I do think it points out is the need for more education for families as to the value of antigen vs. PCR tests.”

She added that all tests have an essential role in the layers of protection, including the vaccines, masking, and ventilation needed to keep kids safe in school.

Researchers analyzed 17 studies to find that lateral flow tests are significantly less accurate in children than adults.

They concluded that rapid tests don’t meet the minimum standards set by health authorities.

Experts say that while the tests aren’t perfect, they’re just one layer of protection, used along with vaccines, masking, and ventilation, to keep kids safe and in school.