Tussle with Pertussis – Whooping cough
Pertussis or whooping cough is caused by the bacterium
Bordetella pertussis. It’s called whooping cough because after a coughing fit, an infected person makes a whooping sound when they try to catch their breath. Babies less than a year old can die from pertussis.
In 2008, about 195,000 children died from pertussis.
http://www.who.int/immunization/topics/pertussis/en/index.html
I want to focus on a ScienceNOW article about new vs. old whooping cough vaccine.
Uptick in Whooping Cough Linked to Subpar Vaccines
Whooping cough, or pertussis, has exploded in the United States in recent years. A new study confirms what scientists have suspected for some time: The return of the disease is caused by the introduction of new, safer vaccines 2 decades ago. Although they have far fewer side effects, the new shots don’t offer long-lived protection the way older vaccines do.
The disease seemed to have disappeared by the 1970s but has come back in the past decade or two. Evidence suggest that the reoccurrence is due to the switch from a vaccine based on the whole-cell bacterium to a new vaccine that has just parts of the bacterium. The newer virus has less side effects but apparently doesn’t offer long term protection. The newer vaccine was developed because the chemicals used to kill the pertussis for the vaccine where causing side effects.
During the 1980s, U.S. parents successfully sued manufacturers, alleging that the whole-cell vaccine also caused long-term brain damage. A 1991 Institute of Medicine report concluded that this was unproven, but by then many pertussis vaccine manufacturers had withdrawn from the market, leading Congress to create a federal vaccine injury compensation program for families who could show a strong case for vaccine damage.
Three studies have shown that the new acellular vaccination, i.e., one based on parts of the bacterium, no the whole cell, is less effective (long lasting) compared to the older vaccine.
Comparative Effectiveness of Acellular Versus Whole-Cell Pertussis Vaccines in Teenagers in Pediatrics: http://goo.gl/SE6dZ , Number and Order of Whole Cell Pertussis Vaccines in Infancy and Disease Protection in JAMA http://goo.gl/H02wy , Reduced Risk of Pertussis Among Persons Ever Vaccinated With Whole Cell Pertussis Vaccine Compared to Recipients of Acellular Pertussis Vaccines in a Large US Cohort http://goo.gl/TBa4H
So why does the whole-cell based vaccine work better and why switch? The whole-cell based vaccine likely works better because there is more of the cell that is presented to the immune system to generate anti-bodies. Also, as the pertussis bacteria mutate, the new vaccine is likely to have less overlap with the mutated version. The older, whole-cell based version is likely to have antigens that are still effective, i.e., still in the mutated version.
Why is this important? There has been an increase in whooping cough out breaks in the US and measles in the UK. http://goo.gl/8xRa7 via Philip Plait and http://goo.gl/fXzB1
It’s dangerous when misinformation and conspiracy theories affect policy and decision making. If more people are scared into not getting vaccinated, then herd immunity is compromised.
Herd Immunity – One Minute Medical School
http://www.health.harvard.edu/video/herd-immunity/
Using science, we understand that the increase in whooping cough infections is at least partially explained by the switch to the new vaccine, based on parts of the Bordetella pertussis and not the whole cell. It is also partially explained by diminished herd immunity by unvaccinated people/children.
Finally, I’ll point you to as disturbing story about anti-vaxxers going after a family that lost their infant to whooping cough. http://goo.gl/saspV
Image Source: http://goo.gl/D31Fo
#ScienceSunday
