Elon Musk, the SpaceX chief executive, has tested positive twice, and negative twice, for the coronavirus after taking four rapid virus tests, he revealed in a disgruntled tweet early Friday morning. The announcement came just days before his company’s much-anticipated launch of a Crew Dragon capsule that will carry four astronauts to the International Space Station.
Antigen tests, which look for pieces of coronavirus protein, are cheap and convenient, typically delivering results to people in minutes. But they are also less reliable than laboratory tests that use a technique called polymerase chain reaction, or P.C.R., which hunts for fragments of genetic material. P.C.R.-based tests are widely considered the gold standard in infectious disease diagnostics.
The Veritor, a product produced by the medical device manufacturer BD, is advertised as having a false negative rate of 16 percent, making it very possible that the two negatives Mr. Musk received had mistakenly missed the virus in his body. But antigen tests are also prone to false positive results, which incorrectly identify healthy people as infected.
Mr. Musk’s testing conundrum arrives at a potentially high-stakes moment. Should he be truly infected, NASA might not allow him to visit with the four astronauts on Sunday, as he did with Robert Behnken and Douglas Hurley before their successful launch in May.
Shortly after tweeting his frustration at his quartet of antigen test results, Mr. Musk told his followers that he had sought out a P.C.R.-based follow-up test, which would deliver an answer within 24 hours.
Just hours later, Mr. Musk, who has repeatedly voiced his frustration with the pandemic and its economic repercussions, took to Twitter again to cast doubt on the validity of P.C.R.-based tests, asking his followers to educate him on whether the diagnostic tools were likely to generate false positives.
Mr. Musk’s announcement of his tests, which was imbued with a similar note of skepticism, was met with a mix of encouragement and jeers. Some people baselessly argued his mixed results were proof that recent rises in coronavirus cases had been inflated. Others pointed out that his repetitive testing struck a discordant tone against the backdrop of a nation in which many are still struggling to access coronavirus diagnostics.