CDC study finds lifting mask mandates, reopening restaurants linked to more COVID cases, deaths Damian Dovarganes/AP FILE - People celebrate Valentineâs Day sitting outdoors under a giant tent at La Boheme restaurant in West Hollywood Sunday, Feb. 14, 2021. (AP Photo/Damian Dovarganes) and last updated 2021-03-05 17:14:53-05 The US Centers for Disease Control and Prevention released a new study that found a link between mask mandates and decreased COVID-19 cases and deaths. According to the study, which compared data in counties where states require masks between last March and December, the spread of the virus slowed when local governments implemented mask mandates within 20 days of implementation.