Testing for antibodies : In hard-hit parts of the United States, including New York, authorities are ramping up another type of testing as they battle coronavirus.
They’re not looking for the virus itself; they’re searching for antibodies.
New York’s Governor Andrew Cuomo started an “aggressive” rollout of antibody testing this week, which would see 14,000 people across the state tested each week.
But many health officials, including those from the World Health Organisation and top US coronavirus expert Anthony Fauci, have warned it’s not the simple silver bullet it might appear to be.
What are antibodies ?
They look for the presence of antibodies, which are a type of protein the immune system creates when it combats a virus.
So here they’re using blood samples to test for antibodies to SARS-CoV-2 (that’s the virus that causes the disease COVID-19).
But those antibodies don’t pop up immediately after someone has been infected, they can take days or even weeks — meaning this particular type of test is good for telling you if you have had the disease at some point, not if you have been recently infected.
Dr Fauci, who is on the White House coronavirus taskforce, says there’s a lot of “misunderstanding” around the tests.
“It’s not saying whether you have the virus now, it’s saying whether you were exposed, infected and likely recovered from the infection,” he told Good Morning America.
So why are the experts worried?
Finding antibodies is one thing; linking it to protection against coronavirus is another.
Dr Fauci says while it’s a “reasonable assumption” that having antibodies equals protection against reinfection, that hasn’t been proven for this virus yet.
“We don’t know how long that protection, if it exists, lasts. Is it one month, three months, six months, a year?” he says.
“We still have a way to go with them.”
WHO emergencies expert Mike Ryan has urged countries to be careful about relying on results from these tests to measure immunity, saying there’s “lots of uncertainty”.
“Nobody is sure whether someone with antibodies is fully protected against having the disease or being exposed again,” Dr Ryan says.
But the organisation as a whole doesn’t have a position on the use of such tests.