Here's How Moderna Plans to Beat the Biggest Threat to Its Vaccine

Moderna's (NASDAQ:MRNA) vaccine is successfully helping people avoid the coronavirus. The billion-dollar product has demonstrated more than 90% efficacy in adults. And new data show it's 100% effective in teens. But Moderna faces one big challenge that could wreak havoc on how well its vaccine protects the population. The vaccine has handled them so far.