Fans celebrate the New Orleans Saints' win against the Indianapolis Colts during Super Bowl XLIV on Bourbon Street in the French Quarter, Sunday in New Orleans. The Saints defeated the Colts 31-17. Cheryl Gerber/Getty Images hide caption

A weakening immune system makes inoculations both more important and less effective for the elderly. But scientists can "trick" the immune system into a younger response by adding a little extra oomph to vaccines for older people via chemicals called adjuvants or larger doses of the vaccines. Nick Ut/AP hide caption

A young boy reacts to receiving a prick from a vaccine. Children can receive up to 13 immunizations by age 2, and many parents worry about possible side effects. But experts say that vaccines are safer and cleaner than before. Jeff J Mitchell/Getty Images hide caption

One week before it was announced the couple would divorce, South Carolina first lady Jenny Sanford and Gov. Mark Sanford hosted a Christmas Open House at the Governor's Mansion in Columbia. Brett Flashnick/AP hide caption

Don DeLillo is the author of 16 novels, including Underworld and Falling Man. His book White Noise won the 1985 National Book Award Nigel Parry/CPi hide caption