How Does the COVID Delta Variant Compare?

In late 2020, a variant of COVID-19 was detected in India that began to quickly spread.

Soon after it received the label “Delta,” it started to become the predominant strain of COVID-19 in countries of transmission. It spread faster than both the original disease and other variants, including “Alpha” that had taken hold in the UK.

Now the COVID-19 pandemic has essentially become the Delta pandemic, as the variant accounts for more than 90% of global cases.

But how does the COVID-19 Delta variant differ from the original disease? We consolidated studies as of September 2021 to highlight key differences between COVID-19 and the dominant variant. Sources include the CDC, Yale Medicine, and the University of California.

COVID-19 vs COVID-19 Delta Variant

At first glance, infections caused by the Delta variant are similar to the original COVID-19 disease. Symptoms reported from patients include cough, fever, headache, and a loss of smell.

But studies showed that the difference was in how quickly and severely patients got sick:

• Spread rate: How quickly the infection spreads in a community (based on the R0 or basic reproductive number). The Delta variant spread 125% faster than the original disease, making it potentially as infectious as chickenpox.
• Viral load: How much of a virus is detectable in an infected person’s blood, with higher loads correlating with more severe infections. Delta infections had a 1000x higher viral load.
• Virus detectable: How long after exposure a virus is detectable in an (Read more...)