The Centers for Disease Control and Prevention updated its mask guidance Friday, advising Americans that N95 masks offer the best protection against COVID-19. At the start of the coronavirus pandemic, the agency recommended Americans not buy N95s to avoid shortages of the protective face masks because they are vital to health-care workers. It now says shortages should not be a problem. Though the CDC emphasized that whatever mask you will wear “consistently and correctly” is the best one, the agency went on to say that N95s “provide the highest level of protection from particles, including the virus that causes COVID-19.”