COVID-19 confirmed case age shifts to young persons under 40

May 29, 2020

As the coronavirus (COVID-19) epidemic passes the peak infection rate in some states and counties, a phased re-opening with changes of stay-at-home restrictions and social distancing recommendations may lead to an increase of non-essential work, social activities and gathering, especially among younger persons. 


A cohort analysis of Washington State Department of Health COVID-19 confirmed case age distribution March 1-April 19, 2020 for proportional change over time using chi square tests for significance. 


·       From March 1-April 19, 2020 age distribution shifted with a 10% decline in cases age 60 years and older and a 20% increase in age 0-19 and 20-39 years.

·        Number of cases over the eight-week analysis period were 0-19 years, 20-39 years, 40-59 years, 60-79 years, 80+ years.

·        New cases increased steadily among 0-19 and 20-39-year-olds.

·        After the peak (March 22, 2020), there was no decline among age 0-19 and a lesser decline among age 20-39 than older groups.

·        As incidence declined in older age groups, the combined percentage of cases age 0-19 and 20-39 increased from 20% to 40% of total cases.


Increased COVID-19 infection among children and young adults is not without serious morbidity and mortality risk to them and others they may come in contact with, indicating a targeted approach for awareness and safety measures is advisable to reduce incidence among the supposedly less vulnerable but more mobile young population age 0-19 and 20-39 years. 

MedRxiv has the release

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