In an upbeat assessment of President Trump’s health, White House physician Sean P. Conley specifically highlighted the new appearance of virus-fighting “IgG” antibodies in Trump’s blood Wednesday. But that positive test is almost certainly the test picking up the experimental antibody drug Trump received last week, not his immune system at work.
To aid his recovery, Trump received a powerful cocktail of two virus-fighting antibodies manufactured in a laboratory. The drug, made by Regeneron Pharmaceuticals, has been shown to help people whose immune systems have a slower or less robust response to the coronavirus.
“Given the volume of IgG antibodies delivered in our therapy, and the timing of these tests, it is likely that the second test is detecting REGN-COV2 antibodies,” said Hala Mirza, a spokeswoman for Regeneron.
In his note, Conley presented the appearance of the antibodies — which were not present when Trump fell ill initially — as a notable sign of Trump’s recovery. But outside experts said that it typically takes more than a week for those antibodies to appear on their own, and the far more likely explanation is that the test picked up the drug the president was given, which has a long half-life.
Regeneron has reported that its antibody drug remains at high levels in the blood for as long as a month after it’s administered.
“President Trump received a huge dose of the Regeneron cocktail,” said Angela Rasmussen, a virologist at Columbia University. Running a typical test that looks for antibodies to the coronavirus spike protein, “they would be almost certain to get a [positive] result and consequently, would have some good news to share about the president’s condition.”