Vaccinations again

There is some essential biology you have to understand before really delving deep into vaccines.  Our immune system is complex, but I'll try to make it easy to understand.

The body's immune system works by first identifying something as a pathogen--a disease causing agent.  Every pathogen is covered with tiny molecules called antigens, and it is those antigens that trigger a specific immune response.  Our bodies don't recognize something just generally as a pathogen; those specific antigens are identified as their own unique pathogens, and the appropriate antibodies are released from the lymph nodes.  We have specific antibodies to fight off specific antigens.   To develop those specific antibodies, though, our bodies have to first be exposed to that disease's antigens.  Some pathogens, specifically viruses, are constantly mutating and having different antigens--this is why when you get a cold, then someone else in your family catches the cold, they don't pass it back to you.  You've been exposed to that specific antigen and have the proper antibodies to fight it off when it gets back in your system.  However, if you are exposed to another cold virus, one that has mutated and has antigens that your body doesn't have the antibodies for yet, you will probably catch it and have symptoms until those antibodies are made and can fight it off.  

This is the science behind vaccinations.  Vaccinations contain dead or greatly weakened pathogens.  Even though they can't cause a child to get sick because they cannot reproduce due to their dead or weakened state, the body still recognizes them as a pathogen.  The body then studies their specific antigens and creates the antibodies specific to those diseases.  If that child is ever exposed to those antigens again, the antibodies will activate and fight off that disease before it gets a chance to reproduce in the body.

(For a much more detailed, yet still easy to understand explanation, check out http://www.howvaccineswork.org/)

Okay, you say.  But I know a lot of people who have been vaccinated who still got the disease, particularly pertussis, or whooping cough.  So how does that work?

This I understand. My parents are both firm believers in vaccinations, and myself and all of my younger sisters have been fully vaccinated.  Yet, several years ago, many of my sisters caught a case of whooping cough.
Whooping cough is, if you want to get technical, caused by B. Pertussis,  fastidious gram-negative coccobacillus.  In real life terms, it is a pathogen that produces toxins that damage the epithelial cells of respiratory tract and causes severe coughing.  This doesn't sound that bad, but, especially in infants and children under 2, that coughing causes a lack of oxygen to the brain, which in turn causes the brain cells to die, causing brain damage.   In classic pertussis, the coughing lasts longer than three weeks, and residual coughing can last for months.   In 2000-2004, there were 6,114 children under twelve months old hospitalized with clinically confirmed pertussis.  Out of that number, 5, 454 had apnea--periods where they stopped breathing.  1,063 had pneumonia, 146 had seizures, and 92 babies died of whooping cough.
             The greatest complications in adults, who usually don't see brain damage, is 5% suffer pneumonia and 4% have rib fractures from the coughing. (http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5517a1.htm#tab2)   The biggest issue with adults having pertussis, though, is that it can be passed on to infants. 

There are two reasons for the pertussis comeback: number one, researchers have found that the efficacy of the pertussis vaccine begins to wear off after around 10 years.  Basically, the body begins to forget those antigens.  This is why you may see commercials on the adult pertussis booster--it isn't a real issue for adults, other than an inconvenience, but it can be deadly when transmitted to an infant.  This is why I got my pertussis booster last year; it isn't something I am overly concerned about dealing with myself, but I would be horrified if I passed it onto my son. 

The other reason there are more pertussis cases is simply because there are fewer people getting vaccinated, something that we'll look at later this week. 
Now why did my family get whooping cough?  Especially when some of my sisters had vaccines that shouldn't have started to wear off yet?
Most likely, they didn't have actual pertussis.  At least not B. Pertussis.  There are other diseases that are in the pertussis family, but that the vaccine does not cover.  These are usually less severe and do not lead to the major complications that the actual B. Pertussis does.  Especially one pathogen called B. Parapertussis presents clinically similar to the deadly pertussis pathogen, but the symptoms are less severe.

Later on this week we'll look at the beginnings of the anti-vaccine movement, which actually began with the pertussis vaccine.