<p>Pertussis Outbreaks and Other Settings with Increased Risk for Pertussis or its Complications: Vaccine providers can administer Tdap to adolescents aged 11--18 years at an interval less than 5 years after Td, particularly when the benefit of providing protection against pertussis is likely to be increased (e.g., pertussis outbreaks and close contact with an infant aged <12 months). The safety of an interval as short as approximately 2 years between Td and Tdap is supported by a Canadian study among children and adolescents. Postexposure chemoprophylaxis and other pertussis control guidelines are available at <a href="http://www.cdc.gov/nip/publications/pertussis/guide.htm%5B/url%5D">http://www.cdc.gov/nip/publications/pertussis/guide.htm</a> and <a href="http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5414a1.htm%5B/url%5D">http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5414a1.htm</a> [3-C].</p>
<p> Shorter interval between Td and Tdap: Tdap may be given at an interval shorter than 10 years since receipt of the last dose of tetanus toxoid-containing vaccine to protect against pertussis. The safety of an interval as short as approximately 2 years between administration of Td and Tdap is supported by a Canadian study of children and adolescents. The dose of Tdap replaces the next scheduled booster dose of Td.</p>
<p> Health-care personnel: Health-care personnel who work in hospitals or ambulatory care settings and have direct patient contact should receive a single dose of Tdap as soon as feasible if they have not previously received Tdap. Priority should be given to vaccination of health-care personnel with direct contact with infants aged <12 months. An interval as short as 2 years from the last dose of Td is recommended for the Tdap dose. Other health-care personnel (i.e., those who do not work in hospitals or ambulatory care settings or who do not have direct patient contact) should receive a single dose of Tdap according to the routine recommendation and interval guidance for use of Tdap among adults. However, these personnel are encouraged to receive the Tdap dose at an interval as short as 2 years following the last Td.</p>