Researchers have found that the newer version of the pertussis vaccine might wear off after only a few years:
An older version of the whooping cough vaccine offered better protection against the disease than the current version does, a new study from Australia suggests.
Children who received the older version of the vaccine were less likely to catch the disease before age 12, compared with those who received the newer version of the vaccine, or a combination of the two vaccines, the study found.
You can read the complete article at: http://vitals.nbcnews.com/_news/2012/07/31/13055892-old-whooping-cough-vaccine-protected-better-than-new 
The article says that the new vaccine was created so it would not have as many side effects. Any thoughts on this study? Do you think it's important for them to create a new vaccine that will last longer?