Preliminary data suggests vaccine effectiveness declined as the Delta variant of COVID-19 spread, although protection against severe disease remained strong, the CDC reports
"'Examining numerous cohorts through the end of July and early August, three points are now very clear,' CDC director Rochelle Walensky said at a White House COVID-19 news briefing Wednesday. 'First, vaccine-induced protection against SARS-CoV-2 infection begins to decrease over time. Second, vaccine effectiveness against severe disease, hospitalization and death remains relatively high. And third, vaccine effectiveness is generally decreased against the delta variant.'" – The Washington Post