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The e-mail, sent out to a listserv for Ardis G. Egan Junior High School in the city of Los Altos on Thursday, April 2, promoted a research study set to begin that weekend.
Weeks later on, early results from Bhattacharya’s team would conclude that, based on the tests, the area had 50 to 85 times more infections than reported cases.
Bhattacharya acknowledged that the email altered the makeup of the research study’s individuals, but argued that the researchers corrected for the difference in volunteers.
Considering that last week, when the Stanford team posted a non-peer-reviewed preprint online, they have actually stirred argument with their findings: that as of early April, in contrast to the 956 cases reported in Santa Clara County, there were an estimated 48,000 to 81,000 infections that had gone unnoticed. And while the death rate from verified cases in the United States is over 5%, due in part to a lack of diagnostic testing, the scientists stated their outcomes suggested the true rate, from identified and undiagnosed cases, was significantly lower: between 0.12%to 0.2%.
Their study, based upon tests administered to 3,330 individuals, is one of the biggest antibody studies in the US so far. Scientists all over the world, from New york city to Germany to Italy, are counting on such tests to help answer among the most important concerns about the infection: how extensive, exactly, it is. Arise from these early surveys vary extensively.
Antibody tests, also known as serology tests, vary from the nasal- and throat-swab tests that can find an existing infection. Instead, these try to find check in the blood that the body immune system had fought off an infection in the past. Federal government officials are promoting them as key to reopening the economy and assisting identify who is safe from reinfection and safe to return to work.
However there are limitations to what antibodies can reveal. With other transmittable diseases, antibodies indicate a procedure of defense versus getting sick again. Nobody understands if that is true of this virus, or, if it is, the length of time such immunity might last.
There are also potential issues with the antibody checks themselves. To quickly increase schedule, the FDA is enabling tests to be offered without the firm independently validating their precision claims. In the US, just four tests have “emergency situation use permission” indicating the agency has reviewed their data– and more than 130 others have unvalidated accuracy rates.
Among these unapproved tests was used for the Santa Clara County study, in addition to for a recent, similar study in Los Angeles County.
But Su’s email to moms and dads at Egan Junior high school, which is attended by more than 650 seventh- and eighth-graders, wrongly described the test as an “FDA authorized antibody test for Coronavirus.”
In reality, the test was dispersed by Premier Biotech in Minnesota, and made by Hangzhou Biotest Biotech of China. As NBC News has reported, China just recently banned the test, along with other COVID-19 tests, from being exported because it had not been vetted by China’s equivalent of the FDA. (The tests used in the two studies were delivered to the United States lawfully, prior to the ban, according to Wired.)
Bhattacharya did not respond to concerns dealing with the false claims made about the test.
Then there’s the question of how to accurately determine a virus’ frequency in a community. To do so, it helps to have underlying test samples from people who are agent of their neighborhood as a whole.
If, for instance, tests are disproportionately done on people who were ill in the past, their positive samples can skew the frequency estimates greater than the real number.
The April 2 email asked for “HEALTHY volunteer[s]” It also discussed that “the disease likely got in the California in December (based on 2019 travel information),” due to take a trip in between the US and Wuhan, China, at that time. And the email described that “the serum antibody test figures out whether your immune system has eradicated the virus and produced antibodies to safeguard you from future exposure.”
Those declarations might make the research study sound especially appealing to people who had COVID-19 signs in the last few months, however weren’t able to get tested.
” It’s troubling in that it appears the phrasing might bias individuals to be most likely to participate in the research study if they thought they have antibodies versus the virus,” Kilpatrick said.
Bhattacharya stated that the issue of sample choice bias would be addressed in the forthcoming revision.
In their preprint, the researchers stated that they ‘d hired participants through locally targeted Facebook advertisements, which led individuals to a study that “supplied info” about the research study. They didn’t share the ads’ language.
The study wound up hiring a group that wasn’t representative of the county as a whole in some ways. Some zip codes were more represented than others– with zip codes in Los Altos comprising some of the greatest concentrations of individuals, according to a figure in the preprint. Bhattacharya acknowledged that the e-mail had contributed to this impact, however argued that he and his team had fixed for the imbalance in their statistical analysis by adjusting for the distinction.
At the bottom of the e-mail, Su described that participating would “contribute to knowledge of the frequency of virus spread in Santa Clara County.”
For additional reading, she linked to a March 24 Wall Street Journal op-ed that argued the number of real infections from the coronavirus was likely much higher than reported, and its casualty rate was therefore most likely to be much lower. The authors were two Stanford teachers, among them her hubby.
