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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) Variants Predominance — Nine States, June–August 2021
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September 10, 2021
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Source: MMWR: Morbidity and Mortality Weekly Report 2021; v. 70 Early Release
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Description:Data on COVID-19 vaccine effectiveness (VE) since the B.1.617.2 (Delta) Variants of SARS-CoV-2, the Virus that causes COVID-19, became the predominant circulating strain in the U.S. 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 Variants accounted for >50% of sequenced isolates in each medical facility’s state. VISION Network Methods have been published (4).
Eligible medical encounters were defined as those among adults aged ≥18 years who had received SARS-CoV-2 molecular tTesting (primarily reverse transcription–polymerase chain reaction assay within 14 days before or 72 hours after the admission or encounter) and a COVID-19–like illness discharge Diagnosis. Vaccination status was documented in electronic health records and immunization registries. Full vaccination was defined as receipt of the second dose of BNT162b2 (Pfizer-BioNTech) or mRNA-1273 (Moderna) mRNA vaccines, or a single dose of Ad26.COV2 (Janssen [Johnson & Johnson]) vaccine ≥14-days before the tTesting or encounter date. Patients who had received no COVID-19 vaccine doses were considered unvaccinated. Patients who had received 1 mRNA dose only or had received the second dose <14 days before tTesting or encounter date were excluded. VE was estimated using a test-negative design, calculating the odds of receiving a positive SARS-CoV-2 test result comparing fully vaccinated and unvaccinated patients (referent group). VE was adjusted for age, geographic region, calendar time (days from January 1 to medical event), and Virus circulation, and weighted for inverse propensity to be vaccinated or unvaccinated (calculated separately for each VE model). VE estimates with 95% confidence intervals (CIs) that did not overlap were considered statistically different. This activity was reviewed by CDC and was conducted consistent with applicable federal law and CDC policy.
Among fully vaccinated patients, the proportion who had received each vaccine product among hospitalizations and ED/UC encounters, respectively, were Pfizer-BioNTech, 55.3% and 53.6%; Moderna, 38.8% and 36.1%; and Janssen, 6.0% and 10.3%. The median interval from becoming fully vaccinated to the hospital admission or ED/UC encounter, respectively, were 110 and 93 days (Pfizer-BioNTech), 106 and 96 days (Moderna), and 94 and 94 days (Janssen).
Suggested citation for this article: Grannis SJ, Rowley EA, Ong TC, et al. 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. MMWR Morb Mortal Wkly Rep. ePub: 10 September 2021.
mm7037e2.htm?s_cid=mm7037e2_w
mm7037e2-H.pdf
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ISSN:0149-2195 (print);1545-861X (digital);
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Pages in Document:3 pdf pages
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Volume:70
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