Learning Objectives for this Presentation:
By the end of the presentation participants will understand factors that contributed to uptake of Tdap in Arizona during a 2005 outbreak.


Background:
On May 19, 2005, record numbers of reported pertussis cases in Arizona prompted the declaration of a statewide pertussis outbreak. Around this time, two new pertussis-containing vaccines for adolescents and adults were FDA-licensed: BOOSTRIX® (May 3, 2005) and ADACEL™ (June 10, 2005).


Setting:
Public and private immunization clinics throughout Arizona


Population:
Residents of Arizona


Project Description:
In response to an increasing number of pertussis cases reported in April and May 2005, ADHS recommended the use of Tdap for adolescents ages 10-18 years, having close contact with infants under age 1, who had not received a Td containing vaccine in the past 5 years. The department issued statewide alerts in May and June encouraging the use of Tdap as an outbreak control measure. Governor's Health Crisis Fund monies were used to purchase 19,090 doses of Tdap for local health department use. Administration of these doses was facilitated by Arizona's school requirement that students receive a Td booster 10 years after their last dose of DTP/DTaP. Immunization registry data demonstrated a dramatic uptake in the use of Tdap vaccine during the outbreak. The percent of adolescents receiving Tdap rose from 11.2% of tetanus-containing vaccinations in June to 82.4% in October (July 46.6%, August 66.7% , September 73.1%). Cases started to decline in August and the outbreak was declared over on October 11, 2005 with 832 confirmed and probable cases reported.


Results/Lessons Learned:
Outbreak control recommendations and public awareness of this outbreak may have led to increased Tdap uptake. At this time Tdap appears to be replacing Td as a booster dose in Arizona. Immunization registries may be helpful in evaluating outbreak control measures relating to vaccine recommendations.