Why the Delta Variant Spread So Quickly

Nature: “Researchers might now know why Delta has been so successful: people infected with it produce far more virus than do those infected with the original version of SARS-CoV-2, making it very easy to spread.”

“Individuals infected with Delta also had viral loads up to 1,260 times higher than those in people infected with the original strain.”

But good news from the New England Journal of Medicine: Two doses of Pfizer or AstraZeneca’s COVID-19 vaccine are nearly as effective against the delta variant as they are against the previously dominant alpha variant.