AZ HEROES Interim Study Findings

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The Centers for Disease Control and Prevention (CDC) published interim study findings on vaccine effectiveness in real world conditions in the Morbidity and Mortality Weekly Report on March 29, 2021

Overview

COVID-19 mRNA (messenger RNA) vaccine effectiveness (Pfizer and Moderna) is not well documented or observed, especially in real-world applications. Using a prospective cohort study with high-risk occupations, AZ HEROES is able to observe the number of new cases after partial and full vaccination.

AZ HEROES interim study findings were published in the CDC Morbidity and Mortality Weekly Report (MMWR). 


Findings

Three groups of participants were analyzed: unvaccinated, partially vaccinated (≥14 days after first dose), and fully vaccinated (≥14 days after second dose).

1.38 positive COVID-19 results per 1,000 person-days were found in the unvaccinated group

0.19 positive COVID-19 results per 1,000 person-days were found in the partially vaccinated group

0.04 positive COVID-19 results per 1,000 person-days were found in the fully vaccinated group


What does this mean?

Estimated mRNA vaccine effectiveness to prevent infection was 80% after partial vaccination and 90% after full vaccination.

Media Contact

Shipherd Reed
Director, Communications and Digital Media
Zuckerman College of Public Health
shipherd@arizona.edu
(520) 626-9669