There's a nationwide scramble to get more doses of the coronavirus vaccine as new cases continue to rise. Nearly 20 million Americans have received at least one vaccine shot. But states are reporting shortages in their supply, amid growing concerns over a new, more contagious variant of the virus. CBS News correspondent Tom Hanson reports on the latest on the pandemic and Dr. Craig Spencer, director of Global Health in Emergency Medicine at Columbia University Medical Center, joins CBSN's Lana Zak to discuss the nation's response to the health crisis. CBSN is CBS News’ 24/7 digital streaming news service featuring live, anchored coverage available for free across all platforms. Launched in November 2014, the service is a premier destination for breaking news and original storytelling from the deep bench of CBS News correspondents and reporters. CBSN features the top stories of the day as well as deep dives into key issues facing the nation and the world. CBSN has also expanded to launch local news streaming services in major markets across the country. CBSN is currently available on CBSNews.com and the CBS News app across more than 20 platforms, as well as the CBS All Access subscription service. Subscribe to the CBS News YouTube channel: http://youtube.com/cbsnews Watch CBSN live: http://cbsn.ws/1PlLpZ7c Download the CBS News app: http://cbsn.ws/1Xb1WC8 Follow CBS News on Instagram: https://www.instagram.com/cbsnews/ Like CBS News on Facebook: http://facebook.com/cbsnews Follow CBS News on Twitter: http://twitter.com/cbsnews Subscribe to our newsletters: http://cbsn.ws/1RqHw7T Get new episodes of shows you love across devices the next day, stream CBSN and local news live, and watch full seasons of CBS fan favorites like Star Trek Discovery anytime, anywhere with CBS All Access. Try it free: http://bit.ly/1OQA29B