Bluebird bio (NASDAQ:BLUE) shareholders had a great day today, with the stock up 32% on some early stage data for LentiGlobin from its HGB-205 study examining the drug as a treatment for beta-thalassemia major. Two patients in the trial have gone off blood transfusions, a new development that has investors excited about the treatment's potential.

So, is the stock a buy?

In the video below, from Market Checkup, the Motley Fool's health care-focused investing show, health care analysts Michael Douglass and David Williamson give their answer.