This spring, Raju Sarker was in respiratory failure. His kidneys had shut down and his blood pressure was falling. Days from death in a Singapore hospital, with his mother back home in Bangladesh saying prayers, something inexplicable happened: He pulled back from the brink.
That was seven months ago. Since then, Mr. Sarker has struggled to regain his full health. The 40-year-old, who worked in Singapore laying internet lines to support his family, has long been free of the coronavirus. But he said his doctors tell him he…