Ask the Experts: Diphtheria: Disease Issues

Results (3)

Yes. Adolescents or adults who have a history of pertussis disease generally should receive Tdap according to the routine recommendation. This practice is recommended because the duration of protection induced by pertussis disease is unknown (waning might begin as early as 7 years after infection) and because diagnosis of pertussis can be difficult to confirm. Administering pertussis vaccine to people with a history of pertussis presents no theoretical risk. For details, visit CDC’s published recommendations on this topic at

Last reviewed: March 31, 2022

Tdap vaccination status does not change the approach to evaluating postexposure prophylaxis when HCWs are exposed to pertussis. Tdap vaccines have an uncertain role in the prevention of transmission of pertussis and herd protection. Antipertussis antibody levels begin to decline precipitously after the first year following a single Tdap vaccination. Healthcare facilities should follow the post-exposure prophylaxis protocol for pertussis exposure recommended by CDC regardless of a HCW’s vaccination status (see HCW can either receive postexposure prophylaxis or be carefully monitored for 21 days after pertussis exposure. Health care personnel should be treated with antibiotics at the onset of signs and symptoms of pertussis and excluded from work for the first 5 days while receiving appropriate antibiotics. CDC supports targeting postexposure antibiotic use to people at high risk of developing severe pertussis, as well as people who will have close contact with others at high risk of developing severe pertussis.

Last reviewed: October 31, 2023

Recent Tdap vaccination does not affect PCR testing. PCR tests are used to detect DNA sequences of the Bordetella pertussis bacterium. PCR tests are very sensitive and could give a false positive result for other reasons. For more information on best practices when performing PCR testing for pertussis see

Last reviewed: October 31, 2023

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