Whooping Cough Pertussis: How Often Is Vaccination Required?

Child Getting Immunized Against Diptheria, Pertussis & Tetanus 

Whooping cough, also known as pertussis, is a respiratory illness caused by the Gram-negative bacterium Bordetella pertussis. This highly contagious disease is spread through airborne droplets, and, once a person is exposed, the incubation time until symptoms emerge ranges from one to two weeks.
Pertussis is known for producing violent coughing fits, which can makes it difficult for the afflicted to breathe. The disease gets its other name, whooping cough, from the "whooping" sound that some sufferers make during severe coughing fits, as they struggle to take in breath.
Whooping cough most commonly affects infants and young children and can even be fatal, particularly in infants.

Pertussis Vaccination

The most effective way to prevent pertussis is through immunization. A combination vaccine is commonly used to protect the recipient form three infectious diseases: diphtheria, pertussis and tetanus. The DTaP is given to children younger than 7 years of age, while Tdap and Td (protecting against tetanus and diphtheria only) are reserved for older children and adults.
The Centers for Disease Control (CDC) currently recommends that children receive 5 doses of DTaP, one dose at each of the following ages: 2 months, 4 months, 6 months, 15-18 months, and then again at 4-6 years.

Incidence of Pertussis Is On the Rise

Over the past few years, there has been an increase in the number of cases, with pertussis outbreaks occurring in several regions of the U.S. In Michigan, an increase in pertussis cases was first observed in 2008 and has continued throughout 2010. In 2010, 9,143 cases of pertussis (including ten infant deaths) were also reported in California, their highest incidence in more than 50 years. Ohio also suffered outbreaks during 2010 and 2011, resulting in the highest oubreak of whooping cough than had been seen in 25 years.The most surprising data that arose during this resurgence of pertussis was that many of the older children who became ill had been fully vaccinated.

New Research Reveals that Additional Pertussis Boosters May Be Required

David Witt, MD, of the Kaiser Permanente Medical Center in San Rafael, California, recently completed a study of Marin County children who became ill with pertussis during the 2010 outbreak. His team found the highest rate of disease among vaccinated children ages 8 through 12.
These results are preliminary, but the data do appear to suggest that the protection against pertussis conferred by vaccination may wane after three years, and that more frequent boosters may be required for full protection against the disease.

Should My Child Be Get Vaccinated Against Pertussis?

It is important to remember that these findings do not mean that the pertussis vaccine doesn’t work. Pertussis vaccines are effective and routinely recommended by the World Health Organization and the Center for Disease Control. The vaccine has saved millions of lives since it was invented in the 1940s. This new information from Witt’s study will be useful in helping health care policy makers determine the most effective pertussis vaccination schedule.
For more information on microbiology and infectious disease see the Virtual Microbiology Classroom of Science Prof Online.

Sources

Centers for Disease Control (2011), Pertussis main page.
Witt MA, et al "Marked acellular pertussis vaccine failure in 8-14 year-olds in a North American outbreak" ICAAC 2011; Abstract B-1697a.