India, Oct. 22 -- As some of the regular readers of this column know, my reading has expanded since March to include dense academic papers published in serious journals that make me wish I had paid more attention to science and math during my college years. Late Tuesday/early Wednesday, two papers that dropped on the journal Science's website piqued my interest. One was titled "Neuropilin-1 is a host factor for SARS-CoV-2 infection" and another "Neuropilin-1 facilitates SARS-CoV-2 cell entry and infectivity". The two papers are already beginning to make waves in epidemiological circles, and have also been reported by some specialised websites. There is a reason for this: 10 months into the pandemic's run, there are still many unanswered questions about Covid-19 and the coronavirus that causes it. This isn't surprising. What is surprising is the pace of scientific research that has helped us answer many other questions about Covid-19 and Sars-CoV-2. Among the important unanswered (or partially unanswered, because we do know some part of the answer) questions are those about the virus's infectivity, and its ability to do more damage than typical respiratory infections do (which it does by targeting other body organs). And the two papers in Science provide answers to these, which would make them among the most important pieces of research on the coronavirus to be published in recent months....