How Vulnerable Are Children to the New Coronavirus?

So far, kids seem to be surprisingly less at-risk to severe infection. But they could play a key role in spreading it, so experts say it’s crucial to follow precautions.

As the new coronavirus spreads, many parents are worried about keeping their kids safe. So far, children seem to be surprisingly less vulnerable to severe infection.

But scientists suspect children could play a key role in transmitting the disease: Reports have shown children have the virus in their secretions for up to 22 days. So it’s still vital to try to prevent them from getting it and spreading it to others.

Only 2% of the patients in a review of nearly 45,000 confirmed Covid-19 cases in China were children, and there were no reported deaths in children under 10, according to a study published in JAMA last month. (In contrast, there have been 136 pediatric deaths from influenza in the U.S. this flu season.) Three percent of Covid-19 cases occurred in people over 80, while 87% were in those 30 to 79 years-old.

About 8% of cases were in people in their 20s. Those 10 to 19 years old accounted for 1% of cases and those under 10 also accounted for only 1%. A separate study looking at the number of infants hospitalized for Covid-19 in China between Dec. 8 and Feb. 6 found only nine infected babies.

“You would think [children] do worse as they do with seasonal influenza but that hasn’t been reported yet,” says Gregory Poland, director of the Mayo Clinic’s Vaccine Research Group in Rochester, Minn.

In the JAMA China study, mortality rates were higher among the elderly: Of confirmed cases, there was a 14.8% fatality rate in patients who were older than 80 and an 8% rate for patients in their 70s. The overall rate was 2.3%. The mortality rates for patients 10 to 19 years-old was 0.2%, and it was 0.2% for patients in their 20s and 30s, as well. It was 0.4% for people in their 40s, 1.3% for those in their 50s, and 3.6% for people in their 60s.

A World Health Organization report on China concluded that cases of Covid-19 in children were “relatively rare and mild.” Among cases in people under age 19, only 2.5% developed severe disease while 0.2% developed critical disease.

“At this point the evidence suggests that children have a reduced risk of developing symptomatic infections,” says Karen Kotloff, head of the division of pediatric infectious disease at the University of Maryland School of Medicine. “They seem to be less likely to become infected and when they get infected they seem to be less likely to develop severe disease.”

Trends in South Korea so far look similar. Among nearly 6,300 Covid-19 cases reported by the Korea Centers for Disease Control & Prevention on March 8, there were no reported deaths in anyone under 30. Only 0.7% of infections were in children under 9 and 4.6% of cases were in those ages 10 to 19 years old.

Typically with the flu and other respiratory viruses, children under 2 are at risk of suffering from complications such as bronchitis or pneumonia because their airways are narrow. These viruses typically cause swelling and inflammation of the airways, says Dr. Poland.

Even though respiratory diseases, such as asthma, are an underlying medical condition that pose a greater risk of serious illness, there haven’t been any reports so far of asthmatic children being hospitalized or dying of Covid-19.

Dr. Poland said some experts speculate that children may not have the same density of the receptors to the virus that adults have. There has also been speculation that children may have more protection due to exposure to other coronaviruses. But Vanessa Raabe, an infectious disease specialist at NYU Langone Health, says there’s not enough data to say that’s the case.

As people age, their immune systems typically weaken, so that could play a role, says Dr. Raabe. Children also don’t smoke, which appears to be a risk factor for those experiencing serious illness.

However, even if they’re not suffering severe symptoms themselves, children may “shed” large amounts of virus and may do so for many days, case reports have found, says James Campbell, a professor of pediatrics at the University of Maryland School of Medicine. Children had virus in their secretions for six to 22 days, or an average of 12 days.

Shedding virus doesn’t always means you’re able to transmit the virus, he notes. But prolonged shedding, high viral loads and children who have no or few symptoms make for a potentially risky combination as families may be unaware their children are contagious.

Some of the best ways to limit the spread, experts say: Make sure kids are washing their hands frequently, keep them out of school and away from other people if they are sick, and clean surfaces often.

If they produce a lot of virus they could “be a powerful vehicle for transmission,” says William Schaffner, a professor in the division of infectious diseases at Vanderbilt University Medical Center.

With influenza, children are a major source of transmission in the community. Studies have shown that if school-based vaccination for the flu happens, there is a decrease in the rate of infections among adults, says Dr. Kotloff. “We don’t have a broad enough experience testing people, especially kids who don’t have symptoms, to have any idea whether that’s true” for Covid-19, says Dr. Kotloff. “But it’s possible that that could be a role that kids play and that has implications.”

School is a breeding ground for spreading infectious diseases. Children, even if they aren’t severely sick, could spread Covid-19 to more vulnerable populations. That is why closing school is an effective strategy to try to contain the virus, experts say.

“You’re trying to decrease the chain of transmission,” says Dr. Poland. “Children are still transmitting the virus to people who have a higher likelihood, based on age and other conditions, of having a severe case or even dying of it.”

Typically if you don’t have a lot of symptoms, you’re less likely to infect someone else since you aren’t coughing or sneezing as much, Dr. Raabe says. But children aren’t as good at covering their nose or mouth when they sneeze or cough. “So it’s concerning that they could be transmitting,” she says.

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