H. Cody Meissner
Everything about COVID-19 is complicated at this time. This report covers a 3-week period in January and February 2020. It is hard to know what can be believed, when data come from China and what may not be the whole picture. This has been the problem all along because the Chinese government is secretive, making it difficult to sort out what's fact and what's not the full story. This report appears to be consistent with our understanding of infection in children. The authors looked at a little more than 2,000 children over the stated time period and attempted to stratify disease severity in these children to understand the spectrum of pediatric disease. The authors present figures such as 90% are either asymptomatic or have mild to moderate disease. The problem is the authors may not have the correct denominator. They don't clearly state how many children were tested. We understand how many got sick, were hospitalized and had chest radiographs.
But it is likely there were so many infected children that the authors didn’t have a full sample size because of the logistical issues. If there were many more children who were asymptomatic or had mild disease who didn’t even see a physician, they would not have been included in the denominator. The data are interesting and a step forward, and I'm glad to see this information, but we have to keep in mind that this may or may not reflect what will happen in other countries, such as the United States.
Why certain age groups get sick and why other age groups don't get sick from a specific virus is not well understood. For example, we know that when poliovirus was present in the U.S., paralysis occurred mostly in young children. Older children, adolescents and adults got infected, but they were less likely to develop paralysis. We know from experience with influenza that severe disease tends to be the other way around.
So far this season, about 25,000 to 26,000 influenza-associated deaths in the U.S. have occurred among adults. To date, fewer than 150 deaths have occurred in the pediatric age group. Children still get infected, but they're less likely to die from influenza. Children are still at risk for severe disease, but they are less likely to die than an adult. The mortality rate is higher for adults. Even late in the season, it is important that as many people as possible are immunized against influenza.
Why is there this discrepancy? Older, frail adults are more likely to have comorbidities such as underlying heart or lung disease. These factors exacerbate the severity of the illness. Most viral illnesses tend to be milder in young children. That explains why there were chickenpox parties, for example. Mothers mistakenly would send their children to the party hoping the child would get chickenpox when they were young and when the disease is less severe than in adults.
It is important to note this is one instance when mother’s advice was not correct, because there were still 100 or 200 deaths in children who had chickenpox in the prevaccine era. Obviously, a mother would experience terrible guilt if she had sent her child to the party, and the child got chickenpox and experienced severe disease. Of course, we now have the chickenpox vaccine and the rates of severe disease have declined dramatically. Every child should be fully immunized against chickenpox. But the point is almost every infectious disease, particularly viral infectious diseases, cause different levels of illness severity in different age groups. Why this is true is not fully understood.
Disclosure: Meissner reports no relevant financial disclosures.
H. Cody Meissner, MD
Infectious Diseases in Children Editorial Board Member
Chief, division of pediatric infectious diseases
Professor of pediatrics
Tufts University School of Medicine