Immunity Against Pertussis Disappearing After Vaccine Dosage Completed?

   

      It's difficult to diagnose.  It's potentially lethal, and it's spreading.  An infectious disease that, until the introduction of the vaccine, was once the leading cause of childhood illness and death during the first half of the 20th century, is back---despite the high rates of children receiving the vaccine to prevent against the disease.
       Pertussis (more commonly referred to as Whooping Cough) is caused by the bacterium Bordetella pertussis (or B. pertussis).  When an infected person coughs or sneezes, tiny germ-laden droplets are sprayed into the air and breathed into the lungs by anyone who happens to be nearby.  Once inside a person's airways, the bacteria multiply and produce toxins that interfere with the respiratory tract.  The bacteria causes inflammation that narrows the breathing tubes in the lungs, causing uncontrollable coughing.
      When a person becomes infected with pertussis, it takes an estimated three to 12 days for signs and symptoms of the disease to occur.  The symptoms are usually mild at first, and may resemble the symptoms of the common cold.  They can include:

*Runny nose
*Nasal congestion
*Red, watery eyes
*Mild fever
*Dry cough

     After a week or two, the signs and symptoms will become worse.  However, if pertussis is diagnosed early, it can be treated with antibiotics. 
     Before a vaccine was available, pertussis claimed the lives of between 5,000 and 10,000 people in the United States each year.  The first vaccine was developed in the 1930s and became widely used in the 1940s.  According to the March of Dimes, a new vaccine called Tdap was introduced in the early 1990s.  But, despite widespread vaccination, there seems to be an unfortunate incidence where immunity is waning.  A study published in the April 2013 edition of the medical journal Pediatrics  set out to determine how long immunity to pertussis lasts after children receive their fifth dosage of the diphtheria, tetanus and pertussis (DTap) vaccine between the ages of four to six years-old.  Joint researchers with the Centers for Disease Control and Prevention (CDC) and the public health offices in Oregon and Minnesota tracked the immunization records of children in both states and compared them with pertussis data.  Their results were startling, as researchers unveiled an increase in the incidence of pertussis in children in the six years after receiving their fifth dose of DTaP, and the incidence of the disease in children aged 7 to 10 years old in Minnesota increased more than sixfold from 2007 to 2010. 
     This study reveals that when matched with similar recent studies, immunity  begins to disappear after vaccination, which according to the researchers, "helps to explain the growing incidence of pertussis in 7 to 10 year-olds who previously had a low risk of disease, presumably due to vaccination with whole-cell vaccines rather than the acellular pertussis vaccine now in use."
     The authors maintain that while new vaccines will be introduced in the future, it's, "important to maintain high immunization rates with existing vaccines to protect vulnerable populations as more disease is circulating in the community."