In 2011, 54% of high school students said they always wore seat belts, the lowest rate of any age group, according to the CDC.

CNN: Fatal wrecks underscore risks for young drivers

While the FDA approved the vaccine for the above age group last December, the CDC is waiting for the efficacy results of an ongoing clinical study (Pfizer expects to complete the trials by 2013) before deciding on broader recommendations.

FORBES: Move up http://i.forbesimg.com t Move down

Rosenberg, who left the CDC in 1999, explained that many of the questions that his group was seeking to answer remain open.

CNN: How the NRA wields its influence

In this study, the researchers tallied a massive amount of NIH and CDC data from 1928 to 2007, breaking it down by age group and coordinating it with periods of economic boom and bust.

FORBES: Suicide and Financial Crisis: How Real Is the Risk?

That's the conclusion of a group of researchers from the Centers for Disease Control (CDC), who collected water samples from 161 filters in public and private swimming pools, as well as water parks in Atlanta last summer.

CNN: Yuck! What's in your pool water

Still, the CDC's David Shay said the 1994 study that took a group of people and gave half of them a placebo and half of them have a vaccine is solid enough evidence that the flu vaccine is very effective.

NPR: Scientists Study Flu Vaccine in Elderly

By contrast, the rate of obesity -- a leading cause of type 2 diabetes in this age group -- was largely flat over the same time period, as previous CDC reports have shown.

CNN: Nearly 1 in 4 U.S. teens facing diabetes