Q&A on COVID-19 Antibody Tests
Much of the focus on COVID-19 testing thus far into the pandemic has been on tests that can determine whether someone is actively infected with the novel coronavirus, or SARS-CoV-2. But, in his drive to “open up America again,” President Donald Trump has turned his attention to blood-based antibody tests, which can show whether someone was previously infected with the virus.
“This will help us assess the number of cases that have been asymptomatic or mildly symptomatic, and support our efforts to get Americans back to work by showing us who might have developed the wonderful, beautiful immunity,” Trump said at an April 17 press conference.
The tests do have the potential to relay valuable information about who might already have immunity and how widely COVID-19 has spread. But so far, the tests are not widely available — and many of those that are available do not work as advertised.
The U.K., for instance, spent $20 million on antibody tests from China that the government subsequently found were not accurate enough to use. An emergency room in Laredo, Texas, also dropped half a million dollars on tests from China that were too unreliable to deploy.
Other tests are better but, like any test, will still miss some people who have antibodies or incorrectly tag others as having antibodies when they don’t. And more fundamentally, experts told us too little is known about how the immune system responds to the new virus to know for sure whether antibodies actually protect a person from contracting the disease.
We’ll run through how the tests work and why it’s so hard to interpret what the results might mean.
What are antibodies and why is it useful to check for them?
Antibodies are specialized proteins that help clear the body of invading microbes. Made by immune cells known as B cells shortly after infection, antibodies specifically recognize pathogens, binding to the surfaces of viruses and stopping them from entering cells, for example, or
