Every Picture Tells a Story: The Delta Variant

By Chuck Dinerstein, MD, MBA — Mar 25, 2022

COVID’s Delta Variant is far more infectious than the earlier versions. It also differs in which age group is most susceptible, as this study from South Korea points out.

Image courtesy of 15734951 on Pixabay

The study is relatively straightforward. The researchers looked at the PCR positive cases before Delta, October 15 to December 22, 2020, and during Delta, June 27 to August 21, 2021

107,000 confirmed infections, 27,000 in the 3^rd wave, 80,000 in the 4^th wave – a 3-fold increased infectiousness
In those age 19 or less, 11% of the confirmed case in the 3^rd wave, 16.7% in the 4^th
In those age 60 or more, 28% in the 3^rd wave, 10% in the 4^th
When adjusted for population percentages, infections in those age 10-15 doubled between the 3^rd and 4^th wave. There was no discernable change between the two waves for those over 50 (except those over 70).

The study comes with limitations, don’t they all? First, this is data from Korea. US data showed no change in hospitalization for children pre and post-Delta. Second, children tend to be asymptomatic so that PCR-proven cases will undercount their infections. The takeaway is that COVID variants mean more than simply being more or less infectious or severe. They target different demographics. And all of these differences may have underlying ethnic distinctions.

Source: Age-Varying Susceptibility to the Delta Variant (B.1.617.2) of SARS-CoV-2 JAMA Network Open DOI: 10.1001/jamanetworkopen.2022.3064 (

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Chuck Dinerstein, MD, MBA

Director of Medicine

Dr. Charles Dinerstein, M.D., MBA, FACS is Director of Medicine at the American Council on Science and Health. He has over 25 years of experience as a vascular surgeon.