https://en.m.wikipedia.org/wiki/SARS-CoV-2_Delta_variant https://en.m.wikipedia.org/wiki/SARS-CoV-2_Delta_variant Delta was named at the end of May 2021 and st

https://en.m.wikipedia.org/wiki/SARS-CoV-2_Delta_variant https://en.m.wikipedia.org/wiki/SARS-CoV-2_Delta_variant Delta was named at the end of May 2021 and started to become the dominant strain worldwide in the following months. As shown in the chart under ”Prevention” (and described in the linked pages), Delta significantly reduced vaccine effectiveness against infection and symptomatic disease, though not against severe disease. However, it’s also true that vaccine effectiveness, regardless of variant, significantly declines over the months following the dose - again, much less so for severe disease than for any symptomatic disease.