SARS-CoV-2, the biological pathogen that causes the COVID-19 disease, is a vicious virus. While much remains to be learned, the new coronavirus seems to be more infectious than the annual flu and possibly more deadly. The unbelievable daily growth in the global confirmed case count speaks for itself. Indeed, confirmed cases of COVID-19 across the globe now exceed 1 million cases？not to mention the death toll that continues to rise. But that’s not the end of this pathogen’s perfidy. Over the past few weeks, an assortment of new studies have shown that asymptomatic carriers―those who are infected with the virus and “shedding” (or spreading) it, but don’t show any symptoms―may be driving the spread of the disease. In other words, people who are sick with COVID-19 may be moving around communities unwittingly, rather than staying at home, because they don’t realize they’re ill and potentially contagious to others. In an interview Monday, Dr. Robert Redfield, director of the Centers for Disease Control and Prevention, noted that “as many as 25%” of infected patients don’t display any symptoms. By Friday evening, the CDC and the White House’s coronavirus task force had endorsed the public’s wearing of nonmedical cloth face coverings？including masks？to help address this concern, especially when social distancing is difficult. The new recommendation shouldn’t threaten the supply of protective masks for health care workers. Elsewhere, a study of roughly 700 infected passengers aboard the Diamond Princess cruise ship estimated that 18% of the cases were asymptomatic. Yet one of the study’s authors noted that the percentage of asymptomatic cases actually could be higher.