Study population and setting
The goal of this study was to examine trends in COVID-19 among young people in the United States and compare these trends against trends seen in adults. Trends in confirmed COVID-19 cases for children, adolescents, and young adults were examined using data on all cases submitted by state and territorial health departments to the US Centers for Disease Control and Prevention (CDC) from March 1 to December 12, 2020. A COVID-19 case was defined as a positive RT-PCR test. Individual-level case reports were stratified into five age groups: 0-4, 5-10, 11-13, 14-17, and 18-24 years old. The weekly percentage of positive tests results was described over time using a daily 7-day moving average, and was calculated as the number of positive results divided by the total number of tests performed per 100,000 persons.
Summary of Main Findings
A total of 2,871,828 cases of COVID-19 among those 0-24 years old were reported to the CDC during this time period. More than half (57.4%) were among those 18-24 years old, while those 14-17 years old made up 16.3% of cases and those 0-4 years old made up 7.4% of cases. Weekly incidence was successively higher with each increase in age group. For all age groups incidence was highest in the final review period (week of December 6, 2020): 99.9 per 100,000 for those 0-4 years old and 379.3 per 100,000 for those 18-24 years old. Trends in positive test results for those 0-24 years old paralleled those of adults (>24 years old) for the whole period, with declines between July and September and then increases seen from September to December 2020. Those 18-24 years old had a slightly earlier peak than all other age groups (early June) and had an additional spike in late August. Data availability on severe outcomes was limited, but among those with available data (41.9% available data for hospitalization, 8.9% for ICU, and 49.1% for death), 2.5% were hospitalized (n=30,229), 0.8% were admitted to the ICU (n=1973) and 0.1% (n=654) died. 73% (476/654) of all deaths recorded were among those 18-24 years old.
The use of cases reported to the CDC is a major study strength as it allows for the examination of a much larger number of cases than a typical study and may get at a broader, more representative sample of the full population of the United States.
As expected from surveillance data, some data elements were missing from reported cases (e.g. indicators of severe COVID-19 illness) and percentages are calculated using available data. These data may be missing asymptomatic and some milder symptomatic cases. This could mean that data representing all of the cases might tell a different story (e.g. percentage of COVID-19 ICU admissions may differ from what is reported here).
While it has been shown that children are susceptible to SARS-CoV-2 infection, but typically have milder illness, this study shows that trends in reported COVID-19 incidence for those 0-24 years old paralleled those for adults, and that there was increasing incidence for each successive age group.
This review was posted on: 12 March 2021