The New York Times reports on a new study finding that the greatest risk to infants of being infected with the bacteria that causes whooping cough, or pertussis, now comes from their older siblings. The Times explains that this is “probably a result of waning immunity among children and adolescents who had received the DTaP vaccine.”
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,