The World Health Organization is recommending healthy people, including those who don’t exhibit COVID-19 symptoms, only wear masks when taking care of someone infected with the contagion, a sharp contrast from the advice given by American public health officials who recommend everyone wear a mask in public. “If you do not have any repository symptoms such as fever, cough or runny nose, you do not need to wear a mask,” Dr. April Baller, a public health specialist for the WHO, says in a video on the world health body’s website. “Masks should only be used by health care workers, caretakers...