Technical CommentsPERTUSSIS

Response to Comment on “The impact of past vaccination coverage and immunity on pertussis resurgence”

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Science Translational Medicine  19 Dec 2018:
Vol. 10, Issue 472, eaau9627
DOI: 10.1126/scitranslmed.aau9627

Figures

  • Fig. 1 Simulated incidence of pertussis in children aged 5 to 9 years.

    The simulated incidence of pertussis (not corrected for under-reporting) under two different scenarios is shown. In the first scenario (blue), there was no switch to the DTaP acellular vaccine from the DTwP whole-cell vaccine (waning rate of DTwP immunity fixed to 0.011 per year) (2); in the second scenario (red), there was a switch to DTaP from DTwP in 1997 for both the primary vaccine course and the preschool booster (waning rate of DTaP immunity fixed to 0.2 per year, giving an average duration of protection of 5 years). For clarity, the y axis is log10-transformed.

  • Fig. 2 Model-based estimates of odds ratios in children aged 5 to 9 years.

    The waning model presented in (2) was extended to incorporate the introduction of the Tdap vaccine booster in teenagers in 2006 in the United States (assuming a Tdap vaccine coverage of 10% in 2006, linearly increasing to 85% in 2012, and plateauing thereafter). Linear regression was used to estimate the yearly relative change in the odds of acquiring pertussis in children aged 5 to 9 years. The analysis was repeated for different assumptions regarding the value of Tdap primary vaccine failure (i.e., 1 minus efficacy on the x axis). The analysis was also repeated for two cohorts of children born during 2001 to 2004 (tracked until ages 5 to 9; resulting study period 2006–2013) and during 2005 to 2008 (study period 2010–2017). Each boxplot is based on 104 model simulations, accounting for parametric uncertainty by sampling from the bootstrap distribution [as was the case for figure 3F in (2)].

  • Fig. 3 Out-of-fit model forecasts of age-stratified pertussis incidence.

    Out-of-fit model forecasts of age-stratified pertussis incidence (not corrected for under-reporting) in 2010 and 2014 are shown. The model consists of data for routine immunization with the DTwP whole-cell vaccine until 1996 (waning rate of 0.011 per year) and subsequently with the DTaP acellular vaccine (waning rate 0.025 per year, corresponding to an odds ratio of 1.38). The model introduced the DTaP vaccine in teenagers in 2006, assuming a primary failure probability of 25% and a vaccine coverage of 10% in 2006, increasing to 85% in 2012, and plateauing thereafter.

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