Two new studies highlight waning mRNA COVID-19 efficacy against infection against the Delta (B1617.2) variant, with one showing that two doses of the Moderna vaccine were highly effective against all variants but that protection against Delta fell over time since vaccination.The other reveals a precipitous drop in mRNA vaccine effectiveness after the emergence of Delta among an older group of US veterans.Efficacy against hospitalization stays highA team led by Kaiser Permanente Southern California scientists evaluated Moderna COVID-19 vaccine effectiveness among 8,153 patients with a positive SARS-CoV-2 test sent for whole-genome sequencing or a negative test from Mar 1 to Jul 27, 2021, before the emergence of the newly recognized, highly