Via Xinhua :
" LOS ANGELES, Sept. 16 : Whooping cough, or pertussis, has claimed nine deaths, all of them babies under three months old in U.S. state of California so far this year, the state Department of Public Health said on Thursday.
Of 196 patients known to have been hospitalized with whooping cough in California, 74 percent were infants under six months old and most of them (57 percent) under three months old, the department said.
This demonstrates that babies are the hardest hit by the disease, said the department.
This year marks the highest number of whooping cough cases in California since widespread vaccination efforts began in the 1940s and '50s."