"There is no doubt, however, that the risk has been, for some years, vastly exaggerated, seemingly to prepare the public mind to accept the new (diptheria) vaccine."--- M. Meadow Bayly, M.R.C.S.,
http://www.alternative-doctor.com/vaccination/16reasons.htm
...in 1969, there was an outbreak in Chicago of diphtheria, and the city board of health reported that 4 of the 16 victims had been fully immunized against the disease and 5 others had received one or more doses of the vaccine. Two of the latter showed evidence of full immunity. A report on another outbreak in which three people died revealed that one of the fatal cases and 14 of 23 carriers had been fully immunized.
There is also evidence that suggests an increase in one's chances of contracting diphtheria once one has been immunized. A classic example of this occurred in Germany during World War II. When diphtheria immunization was made mandatory, there was a 17 percent increase in the number of cases, and a 600 percent rise in the number of deaths from diphtheria. When the vaccine was stopped at the end of the war, the incidence of diphtheria dramatically declined, despite the poor living conditions and malnutrition.