The ugly (buried) truth about the pertussis vaccine
by Jeremy R. Hammond | Sep 14, 2015
The New York Times reports that the greatest risk to infants of pertussis infection comes from older siblings, but leaves out key parts of the story.
The New York Times reports on a new study finding that the greatest risk to infants of being infected with the bacteria that causes
Indeed, waning immunity is a serious problem with the DTaP combination vaccine (which contains diptheria, tetanus, and pertussis antigens). One recent study published in Pediatrics concluded, “Tdap protection wanes within 2 to 4 years. Lack of long-term protection after vaccination is likely contributing to increases in pertussis among adolescents.”
But the Times is misleading its readers by telling only one part of the story, leaving readers with the impression that simply giving more “booster” shots would solve the problem.
Vaccinated Individuals Spread Disease
Waning immunity by itself doesn’t explain the trend described. As another recent study in the journal Clinical Infectious Diseases points out, “pertussis is currently the least well-controlled vaccine-preventable disease despite excellent vaccination coverage and 6 vaccines doses recommended between 2 months of age and adolescence” (emphasis added).
Undervaccination is hardly the problem.
One critical piece of information the Times doesn’t indulge its readers with is that the vaccine does not prevent transmission of the disease. Instead, vaccinated individuals may become asymptomatic carriers.
A study conducted by the FDA and published in PNAS found that vaccinated baboons “were protected from severe pertussis-associated symptoms but not from colonization, did not clear the infection faster than naive animals, and readily transmitted B. pertussis to unvaccinated contacts.”
The researchers reasoned that this was due to the differences between the kind of immunity conferred by natural infection and that conferred by the vaccine. Natural infection confers a robust cell-mediated immunity that vaccination actually prevents by favoring humoral immunity, which is to say the vaccine stimulates the production of antibodies but not the “memory” cells required for robust and long-lasting immunity.
As the FDA summarized in a press release, their findings suggested that “although individuals immunized [sic] with an acellular pertussis vaccine may be protected from disease, they may still become infected with the bacteria without always getting sick and are able to spread infection to others, including young infants.”
The director of the FDA’s Center for Biologics Evaluation and Research, where the study was conducted, described it as “critically important to understanding some of the reasons for the rising rates of pertussis”.
The New York Times, incidentally, did at the time report the findings of the FDA studythat “people recently vaccinated may be continuing to spread the infection without getting sick.” It quoted the lead author of the study explaining, “When you’re newly vaccinated you are an asymptomatic carrier, which is good for you, but not for the population.”
That is the opposite of what parents are typically told about the need for vaccinations, that the “herd” needs to be vaccinated to protect those too young to receive the vaccine: infants. In fact, the logical conclusion of this finding is that parents who vaccinate a child who has an infant sibling are putting the infant at risk.
And it is infants, not older children, who are most at risk of developing serious complications from the disease.
Needless to say, that risk is not something parents are routinely informed of during visits to their pediatrician’s office (or by the media, as the Times so aptly demonstrates in this example).
But that’s not all. There is another risk of vaccination that parents are not being told.