Secondary cases of Hib disease (illness occurring within 60 days of contact with a patient) occur but are rare. Secondary attack rates are higher among household contacts younger than 48 months (2.1%), especially those younger than 12 months (6%) and younger than 24 months (3%). Data are conflicting on the risk for secondary illness among child care contacts, but it is thought to be lower than among household contacts. Rifampin is recommended for chemoprophylaxis because it achieves high concentrations in respiratory secretions and eradicates nasopharyngeal carriage in more than 95% of carriers.
Index patients who are treated with an antibiotic other than cefotaxime or ceftriaxone and are younger than 2 years of age should receive rifampin prior to hospital discharge. Because cefotaxime and ceftriaxone eradicate Hib colonization, prophylaxis is not needed for patients treated with either of these antibiotics.
Rifampin chemoprophylaxis is recommended for all household contacts in households with members younger than 4 years who are not fully vaccinated, households with a child younger than 12 months who has not completed the primary Hib series, or households with a contact who is an immunocompromised child regardless of that child’s vaccination status.
Rifampin chemoprophylaxis is recommended in child care settings when two or more cases of invasive Hib disease have occurred within 60 days and unimmunized or underimmunized children attend the facility. When prophylaxis is indicated, it should be prescribed for all attendees, regardless of age or vaccine status, and for child care providers. See the current AAP Red Book chapter on Haemophilus influenzae infections for more information on this issue.
There are no guidelines for control measures around cases of invasive nontype b H. influenzae disease. Chemoprophylaxis is not recommended for contacts of persons with invasive disease caused by nontype b H. influenzae because cases of secondary transmission of disease have not been documented.