With all people ages 16 and up now eligible for COVID-19 vaccination throughout the United States and adults and older teens getting vaccinated throughout the world, you might be wondering what’s happening with children and COVID-19. You may be wondering whether the perspective on pediatric COVID-19 is changing, with schools reopening, yet with with government approvals for pediatric vaccination lagging behind the approvals that have allowed immunization of adults to advance rapidly.
As far as the risk goes for children who become infected with SARS-CoV2 (the virus that causes COVID-19), as during the early months of the pandemic, children still appear to be a much lower risk of developing disease and severe disease compared with adults, especially older adults. Generally, when children do develop symptoms, they are mild, cold-like symptoms. However, the percentage of infected children who develop severe disease is not zero. It is difficult for health authorities to work out the exact number, because, as with adults, many children with an asymptomatic SARS-CoV2 infection do not get tested, so their positive status is not recorded, but a small percentage of infected children —below 1 percent and probably below 0.1 percent (1 per 1,000) in school aged children, and still much lower in very young children— develop a complication called multi-system inflammatory syndrome in children (MISC, or MIS-C). When first described last year as a complication of SARS-CoV2 in children, MISC was thought to parallel a condition called Kawasaki disease, featuring fever, rash, peeling skin, and inflammation of medium-sized blood vessels. Over time, pediatricians came to see MISC as a separate entity from Kawasaki disease, although there is overlap between the two conditions in very young children, in whom MISC is very rare anyway in comparison with school aged children.
By definition, MISC involves inflammatory complications of at least two organ systems, the most common two affected systems being the cardiovascular and gastrointestinal. MISC must be suspected and ruled out in a child who tests positive for SARS-CoV2, or who has suffered a SARS-CoV2 infection within the past month, who presents with symptoms and signs, such as fever (more than 24 hours), abdominal symptoms (pain, vomiting, and/or diarrhea), low blood pressure, rapid breathing, rapid heartbeat, rash, swollen lymph nodes, conjunctivitis (red eyes), and fatigue, and it need not be all of these together. Because the cardiovascular system is one of the systems that can be affected, it is possible that the child’s blood pressure can plummet, leading to shock. All such cases require admission to a pediatric intensive care unit (PICU), as do many of the cases of MISC without extreme cardiovascular effects. Fatal outcomes are possible in cases of MISC that are not recognized early and treated. Whereas the adult deaths from COVID-19 number on the multiple hundreds of thousands in the United States, pediatric deaths number in the hundreds, most of those being in older children and teens.
To explain why symptomatic COVID-19, especially severe COVID-19, is increasingly rare with decreasing age, scientists have hypothesized that perhaps young children have fewer ACE-2 receptors on their body cells, especially on the cells of the air sacs in the lungs, where the virus enters the circulation. As we have discussed in previous posts, ACE-2 is a protein that many types of body cells display on the outer surface of their cell membranes. Using the spike protein that projects from their surrounding coats, SARS-CoV2 viral particles attach to the ACE-2 and utilize it to invade the cell. This not only spreads the virus through various body tissues, but distracts the ACE-2 from doing its normal job, leading to various symptoms.
Given the fact that children can get severely ill and possibly die from SARS-CoV2, plus the fact that children, especially older children and teens, can spread the virus as easily as adults can, the number of pediatric cases is expected to rise as schools continue to re-open, many of them in hybrid mode. However, the vaccines are poised to help. At the time that I’m writing this in late April, the Pfizer-BioNtech vaccine is waiting for the US Food and Drug Administration (FDA) to extend the emergency use authorization from age 16+ down to age 12+, which would allow most middle school and all high school students to be vaccinated. This is based on clinical trial data showing the Pfizer-BioNtech to be 100 percent effective in the 12-15 year age group (which is even higher than in adults). Meanwhile, the Moderna and Johnson and Johnson (Janssen) vaccines, both of which are authorized in ages 18+, have been in clinical trials in the 12-17 year age group. Of these two vaccines, we can expect that Moderna will receive an EUA extension down to age 12, not long after the Pfizer-BioNtech receives it. As for the Janssen vaccine, the FDA and the US Centers for Disease Control and Prevention (CDC) have ended the pause, so we can expect that it will follow Moderna in receiving an EUA extension down to age 12. Soon, we may also be hearing about a possible EUA for adults to receive the Novavax vaccine, which we also have discussed in a previous post. As for younger children, COVID-19 vaccine trials are in progress in children ages 11 years down to six months, but they are not as far along as the trials for ages 12+, so it will be many months before grade school children are able to be vaccinated.