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  • Pima County COVID-19 testing study makes headlines in national epidemiological journal

    Jan 27, 2021 | Read More News
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    COVID testingA Pima County-based study of a potentially promising COVID-19 screening method appears as a featured entry in Morbidity and Mortality Weekly Report, a prestigious national medical journal published by the Centers for Disease Control and Prevention. The report examines the effectiveness of Abbott Laboratories' BinaxNOW rapid antigen test compared with PCR testing at identifying people infected with the COVID-19 virus.

    For the study, researchers collected specimens from 3,419 people at two community testing sites sponsored by Pima County over a two-week period in November. Each study participant received two tests, the rapid antigen test along with a RT-PCR or real-time reverse transcription–polymerase chain reaction test.

    Data analysis found the antigen test, which detects viral DNA from a respiratory sample like a nasal swab, was less sensitive than RT-PCR test in both symptomatic and asymptomatic people, though sensitivity was increased for those who presented with symptoms consistent with COVID-19.

    This means that BinaxNOW antigen tests have a higher chance of false negatives, especially among people without symptoms; a negative result may not rule out COVID-19 infection. However, BinaxNOW performed fairly well at detection of individuals who have enough virus to be contagious.

    "Antigen tests offer results more rapidly and at a lower cost than PCR tests, so they can be an important tool in an overall community testing strategy," Pima County Health Department Director Theresa Cullen said. “The information gained from this study supports our decision to use rapid antigen tests for routine use in certain settings such as long term care centers. The findings will guide us as we explore other ways we might use these test kit in our community.”

    The County's role in the research included connecting the CDC team with Paradigm Laboratories, the firm which operated the testing clinics, assisting with the development of the study's protocols, data processing and transmission, providing the test kits, and translating materials into Spanish. County staff also provided results to participants who tested positive.

    “We are extremely grateful to everyone who participated in the study and answered lots of questions," Cullen said. “Anyone who’s had a nasal swab can appreciate that those people endured three of them for the study.”

    The CDC chose Pima County to host the study because of the high number of COVID-19 PCR tests conducted, Pima County Health Department’s ability to coordinate with the reference laboratory, and our diverse patient population. 

    “Working closely with the CDC team as well as the Arizona Department of Health Services has helped immensely to improve our ability to respond to the pandemic,” Cullen said. “This work  will also help build our relationship with the CDC for future endeavors.”

    Public health departments continue to test various strategies to reduce or prevent COVID-19 transmission, including expanded screening testing for asymptomatic people. Because estimates suggest that over 50 percent of transmissions occur by way of people who show no symptoms at the time, expanded rapid screening testing will remain an essential part of the strategy to stop the spread of the virus in certain situations.