What's new: Scientists announced Wednesday they have successfully developed three key advances toward a possible pandemic flu vaccine — and it's one that could eventually be delivered to your doorstep via the mail, and be self-administered.
Why it matters: One of public health officials' greatest fears is another flu pandemic that could kill millions. It's not a question of if another one occurs, but rather when. Pandemics can kill large amounts of people worldwide. The largest influenza pandemic, known as the Spanish flu, occurred 100 years ago. It killed at least 50 million people.