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  • Researchers have found that tracking asymptomatic COVID-19 cases in children could help prevent outbreaks.
  • Experts say identifying these “silent carriers” may be as effective at stopping disease outbreaks as vaccinating them against the disease.
  • No COVID-19 vaccine is currently authorized for use in children under the age of 16.

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Quickly identifying children who silently transmit the virus that causes COVID-19 may help curb outbreaks as effectively as vaccinating them against the disease, a new study found.

Researchers from across the United States and Canada developed a simulated model of how the virus is transmitted that takes into account different age groups, the natural history of pandemic disease, vaccination, and interventions like self-isolation.

They concluded that it’s important to start contact tracing at the first sign of infection instead of waiting for test results.

“A substantial proportion of COVID-19 cases are attributed to silent transmission from individuals in the presymptomatic and asymptomatic stages of infection,” the study authors wrote.

Researchers used data from published literature and census data to create a “synthetic population” representative of U.S. demographics. The model looked at six age groups: 0–4, 5–10, 11–18, 19–49, 50–64, and 65 years or older.

They used this model to simulate the effect of isolating asymptomatic children to reduce COVID-19 rates during the course of a year.

In addition to modeling isolation of symptomatic cases within 24 hours of symptom onset, researchers assumed that adult vaccinations would reach 40 to 60 percent coverage.

Their goal was finding the optimal intervention strategy to reduce disease in asymptomatic children to less than 5 percent.

According to the study findings, an approach that identified 11 percent of silent cases among children within 2 days, and 14 percent within 3 days after transmission would bring infection rates below 5 percent with just 40 percent of the adult population vaccinated.

Dr. Lorry Rubin, director of pediatric infectious diseases at Cohen Children’s Medical Center of New York, told Healthline that just like adults, children can contract the virus and have no symptoms, yet transmit it to other people.

“Infected children and adults who develop symptoms are contagious and can spread the infection before they develop symptoms and know they are sick,” he said.

Dr. K.C. Rondello, university epidemiologist and special adviser to The Office of University Health and Wellness at Adelphi University, said COVID-19 has been able to spread so widely due in part to asymptomatic transmission.

“If you can identify the ill by their signs and symptoms, it provides clinicians with a foothold in implementing mitigation strategies,” he said. “On the other hand, if people do not know that they are sick or that they pose a risk to others, public health efforts are severely handicapped.”

Rondello said that it was first thought that only a small amount of cases didn’t have symptoms or only had mild symptoms.

These could include cases such as:

  • asymptomatic, showing no symptoms
  • presymptomatic, hasn’t begun to show signs or symptoms
  • pauci-symptomatic, having signs and symptoms so mild they’re not associated with illness

But as the pandemic progressed, so did our understanding of the disease. Rondello admitted that it’s now believed nearly half of all COVID-19 cases are asymptomatic.

“This makes controlling the spread of illness exceptionally challenging,” he said. “And why we cannot rely upon mitigating the illness by asking sick people to stay at home as a singular, stand-alone strategy.”

Rondello added that this fact is why many public health protective measures, such as masks and social distancing, are so critical.

According to the study, if asymptomatic cases in children remain undetected, achieving below 5 percent rate of transmission would mean vaccinating 81 percent or more of this age group. Something the study authors admit is “unrealistically high.”

They concluded that without vaccines for children, rapidly identifying “silent infections” in children could significantly reduce disease burden.

“These findings suggest that without measures to interrupt transmission chains from silent infections, vaccination of adults is unlikely to contain the outbreaks in the near term.”

According to Rubin, the risk of disease transmission from children to adults has been lower than from adults to children.

But he cautioned that as a higher proportion of adults are vaccinated, resulting in a significant reduction in spread between them, children will become the source of most new adult COVID-19 cases.

Asked how asymptomatic children with the virus can be identified to prevent disease spread, Rubin said rapid testing is key.

“The most effective way is by swabbing and performing rapid tests routinely in children, perhaps once a week,” he said. “This might become even easier with use of saliva as the specimen that may be nearly as useful as swabs.”

According to another recent study, kids rarely develop COVID-19 with debilitating symptoms.

However, if children do develop COVID-19, even if they have a mild case, they can still develop a potentially life-threatening condition called multisystem inflammatory syndrome in children (MIS-C).

While children likely aren’t super-spreaders of SARS-CoV-2, as they can be for diseases like influenza, the emergence of COVID-19 variants combined with rising adult vaccination rates means that children and adolescents might soon contribute more to disease spread.

“Please understand, this B.1.1.7 variant is a brand new ball game,” Michael Osterholm, PhD, director of the Center for Infectious Disease Research and Policy (CIDRAP) at the University of Minnesota, said in a statement. “It infects kids very readily.”

Rubin explained that this study predicts that a program with rapid testing of children exposed to the virus, or routine rapid testing of schoolchildren and isolating those who test positive, will markedly reduce overall cases.

“This was the case even if a relatively small proportion of children choose to take part in routine testing,” he said.

Rubin pointed out that we need to be skeptical of studies that model and predict the future because they’re very dependent on rates and assumptions entered into the calculations.

However, “In this study the assumptions seemed reasonable and therefore it is likely their model has merit,” he said.

According to Rondello, since vaccination isn’t a viable strategy for children at this time, “Public health authorities must redouble their efforts to mitigate spread in minors using the other tools at their disposal.”

Researchers used computer modeling and found that rapidly identifying asymptomatic COVID-19 cases in children could help prevent outbreaks as effectively as vaccinating them against the disease.

Experts say that without identifying these ‘silent carriers,’ adult vaccination programs may not be successful.

They also say new COVID-19 variants, unlike the initial virus, readily develop in children, potentially making them a significant source of new adult cases.