Antibody tests are “not very useful” for making back to work decisions during COVID-19, they are good to get hard data on virus penetrance within communities, attack rate over time and insights into whether social distancing is flattening the curve, according to Dr Kevin Roth, chair of pathology and cell biology at Columbia University Vagelos College of Physicians and Surgeons and pathologist-in-chief at NewYork-Presbyterian/Columbia University Irving Medical Center.
In New York City, the US coronavirus epicenter, a shade more than 2 in 10 people (21%) have tested positive for antibodies to fight off the virus. In upstate New York, the number is far less, with 3.6% people testing positive for antibodies. This is very preliminary data from a first phase, small sample survey of about 3,000 people who were out and about, which means they were feeling well enough to be out in public spaces. New York's antibodies survey was done at 40 locations in 19 counties.
The New York antibody study is the latest in a series of similar tests across America. In Santa Clara, California and in some Los Angeles counties too, the numbers hover at around 3 percent of people having antibodies. The US FDA has granted permission for physicians to use antibody-rich plasma to treat coronavirus patients.
Columbia University Irving Medical Center has developed and validated a serological test for antibodies against COVID-19 and started screening survivors for antibodies that could be used to treat others.
Are these tests reliable? Roth says it depends on “specificity and sensitivity” of individual tests.
“The vast majority of serological tests simply document that a person has had an immune response against COVID-19. The tests do not determine if a person is truly “immune” to future infections or even if someone was truly immune, the tests would not be able to predict how long the immunity would last for”, according to Roth.
Roth said “immunity passports” that lean on antibody tests are “highly unlikely”. Roth’s colleague Dr. Eldad Hod spoke in some detail about Columbia’s own serological tests and the place these tests occupy in the wider arc of community health and the post-COVID19 reopening scenario.
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