As officials in Texas and Mississippi lifted statewide mask mandates, researchers at the Centers for Disease Control and Prevention offered fresh evidence of the importance of mask use in a new study on Friday. Wearing masks, the study reported, was linked to fewer infections with the coronavirus and Covid-19 deaths in counties across the United States The researchers also found that counties opening restaurants for on-premises dining — indoors or outdoors — saw a rise in daily infections about six weeks later, and an increase in Covid-19 death rates about two months later The study does not prove cause and...