COVID-19 has been a more serious and dangerous disease among older people. Most children are at low risk of serious disease and vaccinating them is mainly about reducing transmission overall. 

That being said, it is still possible for children to get COVID-19, and the percentage of cases that kids make up is growing, primarily due to 1) high vaccination rates among older people and lower rates among younger people, which is helping to protect older people against transmission, 2) social factors such as school and school-activities, 3) the high transmissibility of Omicron, and 4) co-infections, especially other respiratory infections which kids are at high risk of.

Regarding low vaccination rates among young people, data from the U.S. Centers for Disease Control and Prevention shows that as of January 13, 2022 in the U.S. only about 18% of kids ages 5 to 11 and 54% of kids ages 12 to 17 are fully vaccinated. As a result, kids are more vulnerable to transmission than other age groups with higher vaccination rates. Combined with the high transmissibility of Omicron and close gatherings of children at school and school-related activities, it makes sense that the proportion of COVID-19 cases among kids is growing.

The percentage of COVID-19 cases that kids make up is also much higher in some places, particularly where vaccination rates are especially low. 

Given that kids are at risk for COVID-19 and seem to be continuing to make up a higher amount of total cases, the COVID-19 vaccines are helpful to protect them against infection. The Pfizer-BioNTech vaccine, for example, was found to be about 91% effective in preventing COVID-19 in children ages 5 to 11 – especially important because 39% of cases in children under 18 are among children in the younger age group. 

The U.S. FDA has given emergency use authorization to a Pfizer-BioNTech COVID-19 vaccine for this age group. Pfizer-BioNTech also applied for an emergency use authorization (EUA) in the U.S. for the vaccine in children ages 6 months to 4 years the last week of January, 2022. the first half of this year. Moderna is also conducting studies of their vaccine in children ages 6 months to 4. 

Without a vaccine, kids are more likely to get COVID-19. One study examined hundreds of pediatric (children) hospitalizations in six U.S. cities in the summer of 2021 and found that almost all of the seriously ill children were not fully vaccinated, indicating how protective the vaccines for kids can be. 

However, overall, children are still less likely to have a severe case that puts them in the hospital compared to other age groups. Up to 50% of children and adolescents might have COVID-19 with no symptoms. 

And as of January 29, 2022, children ages 0 - 4 in the U.S. were hospitalized at a rate of 4 hospitalizations per 100,000 cases, and children ages 5 - 17 were hospitalized at a rate of 2 hospitalizations per 100,000 cases. Compared to 6.7 hospitalizations per 100,000 in the 18 to 49 group, 14.6 hospitalizations per 100,000 in the 50 - 64 group, and 35.7 hospitalizations per 100,000 in the 65+ age group, severe cases warranting hospitalizations among children is low. 

However, that does not mean that without a vaccine kids are very likely to have a severe case. While we are seeing the hospitalization rates increase for infected children, especially ages 0 to 4, children overall still have a much lower risk of becoming severely ill than adults, even with Omicron. In addition, young children seem to have a lower chance of needing ventilators than children hospitalized during previous surges. 

Whether or not Omicron is specifically more severe for children than other variants of COVID-19 is a question that’s still being researched, but early data suggests that not only is Omicron likely not more severe than previous variants, it actually appears to be causing milder illness in children than Delta.

The main concern for kids who get COVID-19 is the risk of multisystem inflammatory syndrome in children (MIS-C). MIS-C is a serious condition in which some organs in the body — such as the heart, kidneys, or brain lungs — become severely inflamed. MIS-C usually occurs weeks after a COVID-19 infection and can impact children who had mild cases or cases without symptoms. Researchers still can’t understand what causes MIS-C but know that it makes the immune system overreact to COVID-19. 

A recent CDC study showed that two doses of the Pfizer-BioNTech vaccine were about 91% effective in preventing MIS-C in adolescents ages 12 to 18.

As protection against COVID-19 among older age groups increases due to higher vaccination rates and boosters – particularly in the U.S. and Europe – there have been trends of more cases among kids making up the proportion of overall COVID-19 cases. This has caused some confusion, which was furthered by an MSNBC appearance by Dr. Zeke Emanuel in which he states that with the omicron variant, kids are likely to either get the vaccine or get a serious condition of Omicron.

Just because a kid isn’t vaccinated doesn’t necessarily mean that they will have a severe case. They are more likely to have a severe case than a kid who is vaccinated, but overall kids (ages 0 - 17) are still less likely to have a severe case of COVID-19 than all other age groups. 

That being said, a vaccinated kid is even less likely to have a severe case than an unvaccinated kid. In addition, vaccines are very protective at preventing MIS-C in kids, which is one of the most concerning conditions among kids caused by COVID-19.

In summary: If an unvaccinated child is infected with COVID-19, including the Omicron variant, they are not very likely to get a serious case of COVID-19. However, they are more likely to get a serious case of COVID-19 than an unvaccinated child. Data is still emerging on if Omicron puts a child at higher risk of a severe case, but early research shows it may be more mild among kids than Delta.