Data on COVID-19 vaccine effectiveness (VE) since the B.1.617.2 (Delta) variant of SARS-CoV-2, the virus that causes COVID-19, became the predominant circulating strain in the United States are limited (1-3). CDC used the VISION Network* to examine medical encounters (32,867) from 187 hospitals and 221 emergency departments (EDs) and urgent care (UC) clinics across nine states during June-August 2021, beginning on the date the Delta variant accounted for >50% of sequenced isolates in each medical facility’s state. VISION Network methods have been published (4).
Interim Estimates of COVID-19 Vaccine Effectiveness Against COVID-19-Associated Emergency Department or Urgent Care Clinic Encounters and Hospitalizations Among Adults During SARS-CoV-2 B.1.617.2 (Delta) Variant Predominance – Nine States, June-August 2021
Authors: Grannis, Shaun J; Rowley, Elizabeth A; Ong, Toan C; Stenehjem, Edward; Klein, Nicola P; DeSilva, Malini B; Naleway, Allison L; Natarajan, Karthik; Thompson, Mark G; VISION Network,
MMWR Morb Mortal Wkly Rep. 2021 Sep 17;70(37):1291-1293. Epub 2021-09-17.