In 1952, public health officials reported infants to be four times more likely than school children and adults to develop meningococcal disease and that the disease was more likely to spread in overcrowded populations. Further, upon evaluation of the four meningococcal disease epidemics occurring between 1915 and 1951, health officials noted that two took place during wartime and two during a time when industrial activities had significantly increased. As a result, they concluded that meningococcal disease outbreaks were more likely to occur during periods of high travel and at times when individuals relocated from a rural setting to more populated urban setting.
In the 1950s and 1960s, meningococcal disease strains resistant to sulfonamides began to emerge, prompting a change in treatment protocols to include the use of antibiotics such as penicillin and chloramphenicol. While penicillin can still be used to treat the disease, medical experts currently consider cephalosporins the antibiotic of choice against invasive meningococcal disease. In 1960, there were 2,259 reported cases of meningococcal disease and the death rate was report to be 0.4 per 100,000 population.
Between 1964 and 1968, meningococcal serogroup B was found to be responsible for the majority of disease cases, however, in 1969, meningococcal serogroup C disease emerged in both military and civilian populations. By 1972, meningococcal serogroup B re-emerged and accounted for the majority of cases. Serogroup C was still found to be responsible for at least one-third of meningococcal cases. When the first meningococcal serogroup A and C polysaccharide vaccines were licensed for use in the United States in 1975, they were ineffective against meningococcal serogroup B, which was the strain responsible for most cases of invasive meningococcal disease. In 1975, there were 1,478 reported meningococcal cases and 308 related deaths.
