Viral shedding
People infected with Delta Variant shed virus before symptoms appear

Symptoms appear 5.8 days after infection and 1.8 days after they first tested positive for viral RNA, shows study. The R0 value for Delta was 6.4, much higher than the original variant’s value of 2-4

What are the differences between COVID-19, MERS and SARS?

On April 17, the journal Science published a study by a group of scientists from the Netherlands, who did a comparative study of the pathogenesis of the three diseases