Which among the following is not true regarding diphtheria carriers?

Immunization doesn't prevent carrier state. It only prevents infection. Human carriers are the main reservoir of infection. Infected patients and asymptomatic carriers can transmit C diphtheria respiratory droplets, nasopharyngeal secretions, and rarely fomites. The greatest propoion of carriers is in the age group 1 to 5 years, and owing to the small size and anatomical complexities of the nasal passages, the pathological conditions tend to persist and make examination and treatment difficult. Treatment of contacts is necessary.