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How Effective is Pertussis Vaccine?
After a century of pertussis vaccination programs, vaccinologists are still unsure how pertussis infections - or many other infections - stimulate long lasting cell mediated and humoral immunity in the body. This lack of basic scientific knowledge relates directly to the inability of vaccine makers to develop and manufacture vaccines that provide long lasting artificial immunity and to the lack of correlates for immunity to accurately measure the kind of immunity vaccines do or do not provide.
Most public health officials maintain that when pertussis vaccine is used on a widespread basis in a population, it appears to lessen the overall incidence of the disease and that vaccinated children have less severe cases of pertussis whooping cough.
However, studies published in the 1980’s reported that the highly reactive whole cell DPT vaccine licensed in 1949 did not prevent infection or transmission, and provided only two to five years of temporary immunity at best. The efficacy of whole cell pertussis vaccine in the DPT shot was measured to be between 30 and 85 percent, depending upon the type of DPT and vaccine manufacturer.
The less toxic acellular DTaP vaccine, licensed in the U.S. in 1991, and currently in use in the United States and other developed countries, has also failed to prevent infection or transmission of pertussis. Studies have also demonstrated that DTaP vaccine provides only between two and five years of temporary immunity from pertussis. Acellular pertussis vaccine efficacy in clinical trials has been measured to be between 40 and 89 percent, depending upon the DTaP vaccine manufacturer.
According to a 2005 study in the journal Pediatrics, pertussis containing DTP and DTaP vaccines were estimated to be from 83.6 percent to as much as 97.7 percent effective, depending on the number of doses administered, the combinations of vaccine used in the shot containing pertussis vaccine, and age of the child at which it was administered. However, a 2010 analysis of a California whooping cough outbreak published in the medical literature revealed that more than 80% of those affected were fully vaccinated and the pertussis vaccine was found to be between 24 and 41 percent effective in children two to 18 years of age three years post-vaccination. In 2010, the Tdap vaccine, recommended in 2006 for adolescents as a booster dose of acellular pertussis vaccine, was found to be only about 66 percent effective.
By 2012, the CDC acknowledged that pertussis vaccine immunity had waned in older children, that DTaP/Tdap immunity begins to wane within five years of vaccination, and that unvaccinated individuals and children with vaccine exemptions were not to blame for the ongoing whooping cough outbreaks.
In fact, child pertussis vaccination rates in the U.S. have remained very high since 1961 and consistently more than 94 percent of kindergarten children have had four to five pertussis-containing vaccines. As well, nearly 94 percent of all children have received at least three doses of DTaP vaccine, and 88 percent of teenagers attending high school have received a sixth pertussis booster shot.
However, reported numbers of pertussis cases differ substantially from the total number of actual cases of pertussis in the United States, as most pertussis cases are not being diagnosed or reported by doctors to the government. Public health officials do not have reliable lab tests to measure pertussis immunity and are unable to agree about how to diagnose pertussis when infected people, especially vaccinated people, are seen in doctor’s offices with mild symptoms. Further, there is evidence that millions of vaccinated children and adults living in the U.S. become infected with pertussis whooping cough but are never identified as doctors are not diagnosing or reporting them. In fact, a person, vaccinated or unvaccinated, can develop a silent asymptomatic pertussis infection and transmit it to another person without even knowing it. Both natural and vaccine acquired immunity is temporary and while vaccination may prevent clinical symptoms, it does not block infection, carriage or transmission.
In fact, a review of the medical literature has revealed that the experts are unhappy with their lack of knowledge of the B. pertussis microbe and are disagreeing with each other about if, when, how and why pertussis vaccines have consistently failed to achieve herd immunity and prevent B. pertussis whooping cough from circulating in highly vaccinated populations around the world.
In 1976, after only approximately 1,000 cases of pertussis were reported in the U.S. , pertussis rates began to climb. In the 1980’s and 1990’s, researchers became aware that the whole cell pertussis vaccine found in DPT was not capable of preventing infection and transmission of the disease. Just like before the introduction of widespread DPT vaccination programs, pertussis increases continued to be reported in cycles of three to five years, including in the U.S. where over 94 percent of children had gotten three to five DPT shots.
In 1988, researchers began warning that the B. pertussis microbe had begun to evolve in order to evade the whole cell pertussis vaccine. The evolving of the B. pertussis microbe had begun following the mass introduction of the DPT vaccine in 1950’s.
In a fight to survive, the B. pertussis microbe has created new strains of pertussis that produce more toxin to suppress the human immune system and cause more serious disease. Today, the pertussis strains included in the vaccine no longer match the pertussis strains causing whooping cough disease. There is compelling scientific evidence that B. pertussis bacteria have evolved to survive vaccine pressure and as a result, there are more virulent pertussis strains that are more efficiently transmitted by vaccinated children and adults with waning immunity. In 2014, public health officials at the CDC and around the world admitted that “most mutations in genes encoding acellular vaccine components arose in the period in which the whole cell vaccine was used.”
Another Bordetella pertussis whooping cough disease, B. parapertussis is also circulating in the United States and elsewhere. B. parapertussis whooping cough can look identical to B. pertussis whooping cough, however symptoms are usually milder. B. parapertussis is increasing in the U.S. and other countries, which have had high pertussis vaccination rates for few decades. There are estimates that perhaps up to 30 percent of whooping cough disease in highly vaccinated populations may be caused by B. parapertussis organisms. Pertussis vaccines widely used around the world do not protect against parapertussis and there is no vaccine for parapertussis.
It is possible to have both B. pertussis and B. parapertussis infections at the same time. B. parapertussis is often milder than B. pertussis but can also involve serious complications, which lead to pneumonia and death.
IMPORTANT NOTE: NVIC encourages you to become fully informed about Pertussis and the Pertussis vaccine by reading all sections in the Table of Contents , which contain many links and resources such as the manufacturer product information inserts, and to speak with one or more trusted health care professionals before making a vaccination decision for yourself or your child. This information is for educational purposes only and is not intended as medical advice.