shown the nurses, we are here to support you, and we have your back like you had ours. >> reporter: for some medical workers, the strain just too much. one nurse in el paso sharing why she resigned last week saying she wishes people had taken precautions more seriously. >> you know, it's kind of a slap in the face when you call us heroes in the spring, and then in the fall, here we are working our butts off, and it doesn't seem like it's helping. people are dying. >> reporter: but hope is on the horizon, promising vaccine news. positive preliminary results from moderna and pfizer. if both qualify for emergency use authorization, 20 million americans could start getting the vaccines as soon as december. lindy washburn is one of the volunteers in the moderna trial, but doesn't know if she got the vaccine or a placebo. >> just being in the middle of it and witnessing this, it feels historic. >> reporter: both vaccines require two doses and use genetic instructions that tell the body to...