The coronavirus played a nasty trick on David Arellano.
When doctors put him into a medically induced coma on April 13 because of a life-threatening case of COVID-19, the Alpha variant of the virus held sway. But by the time they started weaning him off sedatives on May 23, the strain gaining dominance was a new version, first identified in India, called the Delta variant.
The new variant, Arellano quickly learned, is mutated enough that the antibodies his body built to fend off his previous coronavirus infection don’t work so well against it.
His immune system and the immune systems of all those who fought off the virus before Delta arrived is aimed at the past, like bottles of expired medicine.