A majority of American adults say they know someone who has been diagnosed with Covid-19, according to new data from the NBC News|SurveyMonkey Weekly Tracking Poll. Sixty-eight percent of adults say they know someone who has had the coronavirus since December, while 31 percent say they don't know someone who has been diagnosed with the virus. Thirty-four percent of adults say either they or someone in their household hse been tested for the coronavirus in the past month, while 64 percent say no one in their home has.