Why does COVID Delta variant spread so fast?

The Delta Variant, which is said to have led the second wave of coronavirus in India, has been a matter of concern for many scientists and experts. The World Health Organization (WHO) recently categorised the deadly variant as a 'variant of concern', stating the serious dangers it can pose to people's health and physical well-being.

Why does COVID Delta variant spread so fast?
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The Delta Variant, which is said to have led the second wave of coronavirus in India, has been a matter of concern for many scientists and experts. The World Health Organization (WHO) recently categorised the deadly variant as a 'variant of concern', stating the serious dangers it can pose to people's health and physical well-being.