By Heather Callaghan

A study just published in BMC Medicine by Santa Fe Institute Omidyar Fellows Ben Althouse and Sam Scarpino used algorithms to see what caused a resurgence of whooping cough (pertussis) in the U.S. and UK.

It has now been openly declared that the DTaP vaccine is causing the uptick in whooping cough.

Out of the hypotheses, asymptomatic shedding was the final detectable problem. However, the authors have more to say on it, some of which sounds very contradictory coming from researchers who have proven that the mechanism of the acellular DTaP is, in part responsible for the spread of a dangerous bacterium.

Highlights, and this writer’s observations:

Researchers hypothesize 4 causes of whooping cough (pertussis) resurgence, zeroing in on low vaccine coverage and unvaccinated populations, failure of vaccine, microbial resistance, and asymptomatic shedding from newer, acellular vaccines.

Vaccinating individuals in close contact with infants too young to receive the vaccine (“cocooning” unvaccinated children) may be ineffective and prove negative.

It isn’t really explained how asymptomatic transmission accounts for infecting the vaccinated population and why even more vaccine coverage would help…

Authors claim that before a new vaccine is ready for clinical use, other options are necessary for reducing incidence, including vaccination of pregnant women.

According to Science Daily’s assessment which focuses on “anti-vaccine” sentiment, the authors vigorously want higher DTaP rates regardless, and present the information for policy and vaccine makers. Other outlets have implicated that a demand for safer vaccines in the 1990s caused the problem, but they dismiss death and injury associated with previous whole-cell vaccines. The burden of safety is to be on the manufacturers.



In the end, more vaccination is called for despite the admission that whooping cough is being spread by the vaccine.

The authors reveal that a newer model of the vaccine is in the pipeline. Just as before, the only time any fault is admitted on the part of a vaccine, there’s another one ready. Yet, lack of vaccination rates will always the focal point even when the vaccine is shown to spread that very disease – in the vaccinated population no less…

Excerpts from the study found here are reprinted with credit under a Creative Commons license:

Asymptomatic transmission and the resurgence of Bordetella pertussis

Authors: Benjamin M. Althouse and Samuel V. Scarpino

Background

The recent increase in whooping cough incidence (primarily caused by Bordetella pertussis) presents a challenge to both public health practitioners and scientists trying to understand the mechanisms behind its resurgence. Three main hypotheses have been proposed to explain the resurgence: 1) waning of protective immunity from vaccination or natural infection over time, 2) evolution of B. pertussis to escape protective immunity, and 3) low vaccine coverage. Recent studies have suggested a fourth mechanism: asymptomatic transmission from individuals vaccinated with the currently used acellular B. pertussis vaccines.



Methods Using wavelet analyses of B. pertussis incidence in the United States (US) and United Kingdom (UK) and a phylodynamic analysis of 36 clinical B. pertussis isolates from the US, we find evidence in support of asymptomatic transmission of B. pertussis. Next, we examine the clinical, public health, and epidemiological consequences of asymptomatic B. pertussis transmission using a mathematical model.



Results [emphasis added by H.C.] We find that:

1) the timing of changes in age-specific attack rates observed in the US and UK are consistent with asymptomatic transmission;

2) the phylodynamic analysis of the US sequences indicates more genetic diversity in the overall bacterial population than would be suggested by the observed number of infections, a pattern expected with asymptomatic transmission;

3) asymptomatic infections can bias assessments of vaccine efficacy based on observations of B. pertussis-free weeks;

4) asymptomatic transmission can account for the observed increase in B. pertussis incidence; and

5) vaccinating individuals in close contact with infants too young to receive the vaccine (“cocooning” unvaccinated children) may be ineffective.