Evidence is insufficient to determine the effectiveness of antibiotics in those who have been exposed, but are without symptoms. Preventive antibiotics, however, are still frequently used in those who have been exposed and are at high risk of severe disease (such as infants). Vaccine
Pertussis vaccines are effective at preventing illness and are recommended for routine use by the World Health Organization and the United States Centers for Disease Control and Prevention. The vaccine saved an estimated half a million lives in 2002.The multicomponent acellular pertussis vaccine is 71–85% effective, with greater effectiveness against more severe strains. However, despite widespread vaccination, pertussis has persisted in vaccinated populations and is today "one of the most common vaccine-preventable diseases in Western countries". The 21st-century resurgences in pertussis infections is attributed to a combination of waning immunity and bacterial mutations that elude vaccines.Immunization does not confer lifelong immunity; a 2011 CDC study indicated that protection may only last three to six years. This covers childhood, which is the time of greatest exposure and greatest risk of death from pertussis.An effect of widespread immunization on society has been the shift of reported infections from children aged 1–9 years to infants, adolescents, and adults, with adolescents and adults acting as reservoirs for B. pertussis and infecting infants who have had fewer than three doses of vaccine.Infection induces incomplete natural immunity that wanes over time.
Dermatosis papulosa nigra (DPN) is a condition of many small, benign skin lesions on the face, a condition generally presenting on dark-skinned individuals. : 638–9  DPN is extremely common, affecting up to 30% of Black people in the US. From a histological perspective, DPN resembles seborrheic keratoses. The condition may be cosmetically undesirable to some. They should not be confused for Leser-Trélat sign, a sudden explosion of lesions due to a growing tumor. Pathophysiology
The pathophysiology of DPN is unknown. Evidence of family history may suggest a genetic propensity. Treatment
DPN lesions are benign and no treatment generally is indicated unless lesions are cosmetically undesirable. Surgical options including curettage, cryotherapy and laser therapy are options. Scarring, postoperative skin discoloration or keloid formation are potential complications. Therefore, conservative DPN treatment is advisable. Prognosis
DPN is not a pre-malignant condition nor is it associated with any underlying systemic disease. DPN lesions show no tendency to regress spontaneously, and often increase in size and number as an individual ages. Epidemiology
DPN affects up to 35% of the African American population in the USA. Insufficient data is available on the international frequency of DPN. Lesions generally emerge during puberty, increasing steadily in number and size as an individual ages. The incidence of DPN lesions increases with age. Black people with a fair complexion have the lowest frequency of involvement. DPN also occurs among Asians and Polynesians, although the exact incidence is unknown. Females are affected more frequently than males.