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Dr. Vinayak Prasad, a San Francisco-based hematologist-oncologist, health researcher, and associate professor at the University of California at San Francisco, excoriated the CDC report, calling it “entirely, irredeemably flawed.”
“Its flaws are so evident that it should not have been published nor promoted.”
In a critique of the study, Prasad noted that just 13.4% of people who tested positive whom researchers had called actually answered the phone and participated in the study, with just 8.9% of people in the negative test group answering the phone.
“When you get a response rate this low you wonder if you are inserting biases you cannot even imagine. Who are the sick COVID people who answer the phone. Are they the least sick ones? The sick ones don’t take calls. Who are the people who answer the phone who test negative? The most anxious ones? The most gullible?”
Prasad also noted that respondents who said they had not spent time indoor settings were removed from the study, as were people who had a known COVID-positive contact.
More significantly, respondents who tested positive tended to undergo testing for different reasons than respondents in the negative cohort, with 78% of positive respondents getting tested because they had symptoms, compared to just 17% of the negative cohort, which had a larger percentage of people who tested just to check if they were infected, because they are required to undergo routine screening, because they are planning to travel, or because they are undergoing a medical procedure.
“Put more technically, the root virtue of test negative strategy (comparability) is violated and unmeasured confounding is injected. Paper cannot be salvaged.”