The U.S. is being hit hard by the coronavirus. But what is particularly staggering is the number of cases among the children under 18.

As of December 31, nearly 2.13 million children in the U.S. had tested positive for COVID-19, according to data released by the American Academy of Pediatrics (AAP). Roughly 128,000 children were diagnosed with COVID-19 last week alone.

Although children's mortality rate remains low, experts still worry that a rise in cases among children may induce a spike in cases of Multisystem Inflammatory Syndrome in Children (MIS-C) later on.

MIS-C is a post-infectious syndrome that can trigger inflammation in the heart, lungs, kidneys, brain, skin, eyes or gastrointestinal organs.

Common symptoms include fever, abdominal pain, vomiting, diarrhea, neck pain, bloodshot eyes and skin rash.

The U.S. Centers for Disease Control and Prevention (CDC) said it still doesn't know what causes MIS-C. However, what they do know is that many children with MIS-C had the virus that causes COVID-19, or had been around someone with COVID-19.

Many experts believe that the surging cases among children, to some extent, relate to school and college re-openings.

Earlier, The New York Times reported that documents and interviews disclosed how top U.S. officials were pressuring the CDC to play down the risks of sending children back to the classroom, and pushing public health experts to use alternate data suggesting that the pandemic posed little danger to children.

However, there are also some scientists who think the evidence is far from sufficient to prove that the reopening of schools should be done responsibly due to the surging cases among children.

The AAP is also pushing for public health officials to study the future mental and emotional effects of the coronavirus on kids.

Data shows the number of children aged 5 to 11 who made emergency room visits for mental health issues is 24 percent higher than a year previously, while visits from children aged 12 to 17 increased by about 31 percent.

Health experts believe the long-term effects of the pandemic will be detrimental to mental health, since it has gone on for over eight months and it is likely to continue to disrupt lives for many more.

Let's take the virus seriously, take your kids' health seriously. Let's wash hands frequently, always wear a mask, avoid close contact with other people, and meanwhile, help your kids cope with stress, stay active, and connected, but on a virtual and remote basis.

Scriptwriter: Pan Zhaoyi

Voiceover: Zeng Ziyi

Cover image: Li Yueyun

Producer: Li Tianfu

Chief editor: Wen Yaru

Director: Zhang Shilei