Background: Pertussis resurgence is evident over the last decades with young infants at risk for severe disease. Given the waning immunity in previously vaccinated individuals and pertussis’ contagiousness, healthcare workers (HCWs) may pose a reservoir of infection for susceptible infants. Accordingly, public-health authorities require that HCW, particularly those in close association with young infants be immunized with Tdap. Since little is known regarding the efficacy of Tdap administered to pediatric HCWs, we sought to study its efficacy among such workers as a function of time.
Methods: The infection control unit manages the HCW immunizations of the hospital employees in accordance with the Israel Ministry of Health guidelines. Although no serological correlate of protection against pertussis is established, 5 IU/mL of ELISA antibodies to Pertussis toxin are considered protective. Subjects were divided into groups depending on whether their ELISA antibodies were above or below this cutoff (EUROIMMUN).
Results: Eighty-seven pediatric HCW (69 female), vaccinated at mean age of 36 years were sampled in a hospital in Northern Israel, October 2018. Amongst the females, there were more with protective levels ≥5 IU/mL than with <5 IU/mL, 49/67 (75%) versus 20/20 (100%), p=0.02, respectively. There were no differences between the protected and unprotected group regarding time elapsed between Tdap administration and antibody sampling, 48.5±26.2 versus 57.0±16.8, p= 0.9. All males’ samples had PT antibody levels ≥5 IU/mL.
Conclusion: Despite compliance with Tdap immunization, nearly a quarter of the females exhibited insufficient PT antibodies. Further pertussis Immunogenicity studies are warranted to evaluate vaccination strategies.
