The Centers for Disease Control and Prevention is looking closely at California whooping cough cases. Researchers are checking to see if the vaccine against whooping cough, also called pertussis, is effective.
The CDC study began in 2007, but research efforts have intensified after pertussis cases continued to rise in California.
The study also comes as other states like Texas and Ohio are seeing increases in the number of pertussis cases.
CDC spokesman Jeff Dimond says the study is routine---and he's urging almost all adults and children to get the shots.
"That means mom, dad, brother, sister, grandma, grandpa, aunts and uncles, day care workers, television repair men," Dimond says. "Anyone that is going to be handling or be working around a newborn infant should have the pertussis vaccination."
CDC officials say the current vaccine is 80-90% effective, although there have been recent media reports questioning that claim.