As we try to predict what will happen here in the US with COVID-19, it’s natural to look at the experience in China, where the epidemic began. In a study published in the journal Pediatrics, we learn about how the pandemic affected children.

What this study tells us

The study looked at information about 2,143 children with COVID-19 infections that were reported to China’s Centers for Disease Control from January 16 to February 8 of this year. Of the infections, about a third were confirmed with a laboratory test for COVID-19. The others were diagnosed based on symptoms and the results of other tests, such as x-rays.

The best news in this study is that 90% of the children had illness that was asymptomatic, mild, or moderate — as opposed to severe or critical. That means that even if the children were sick, with fever and cough, 90% did not have trouble breathing, need oxygen or need to be in the intensive care unit. While 4.4% were reported as asymptomatic, given that only a third had laboratory testing, it’s very likely that the actual number of asymptomatic infections in children during that time period was higher. Only one child died.

In adults, it appears that more like 80% have mild to moderate infections. We don’t know why children appear to have milder disease overall. It’s likely a combination of factors related to body chemistry, immune function, and even social factors such as how children are cared for and spend their days. But whatever the reason, it’s good news.

What else is important to know

However, there is a part of the study we need to pay attention to: younger children are at higher risk of running into trouble. Among children less than a year old, 10.6% had severe or critical disease. For children ages 1 to 5, that number was still high at 7.3%. It dropped to 4.2% for 6-to-10-year-olds, 4.1% for 11-to-15-year-olds, and 3% for those 16 and older. Interestingly, the only child who died was 14 years old.

It’s not really surprising that the youngest children, especially infants, are more vulnerable. In most epidemics, such as influenza, it’s the very young and the very old that have the highest risk.

How can this information help us?

How can we use this information? Aside from all the advice already given to parents about hand washing, social distancing, and maintaining healthy habits, parents of young children should take extra care.

Be especially careful about who has contact with your young children

Choose caregivers carefully. Limit the number overall, and choose those who have limited contact with other people and who can be trusted to practice social distancing, wash their hands frequently, and stay away if they feel at all sick.

Limit the number of people who have contact with or hold young children.

To the extent that it is possible, keep young children at home. If you take them out, keep them inside strollers or otherwise limit what they touch.

Wash their hands even more often. They just can’t stop themselves from touching things and touching their face.

Be particularly watchful should young children get sick

Call your doctor for advice rather than bringing your child in for mild or moderate illness (there’s nothing your doctor can do at the office, and you are just adding the risk of more exposures). However, you should absolutely seek medical care if your child has

any trouble breathing — rapid or forceful breathing, a pale or blue color to skin, trouble feeding or talking, or doing usual activities because of breathing problems

a high fever you can’t get down (while it’s not certain, there have been some concerns raised about using ibuprofen with COVID-19 — out of an abundance of caution, best to use acetaminophen instead)

unusual sleepiness

pain or irritability you can’t soothe

trouble drinking or refusal to drink, and is making less urine.

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For more information on coronavirus and COVID-19, see the Harvard Health Publishing Coronavirus Resource Center.