What Will It Take to Stop the Delta Variant?

A more powerful driver of Covid-19 outbreaks than any strain of the coronavirus encountered so far, the delta variant is testing the limits of public health defenses globally. The good news is that in most cases, the effectiveness of vaccines at protecting against severe disease is maintained; the vast majority of infections are occurring in unvaccinated people. But vaccines alone don’t provide a fail-safe shield. Increasingly, public health specialists stress that countering delta will require multiple strategies.

Delta is both more infectious and more capable of evading immunity generated by either vaccination or a previous natural infection. It’s not known exactly why, but scientists believe it’s probably a combination of factors, including that: