Sunday, May 13, 2007

Vaccination Scars: Hypertrophic Scar or Keloid

Have you ever noticed the vaccination scar that all Taiwanese have on their upper arm in the deltoid area? Ever wondered why you don't have it? It's a topic, I believe, that has never been focused on in any blog so far.

I have to say that it really took me a while to track down the information for this blog entry. I profess my stupidity about all things medical. When I really got down to it, though, I found a great explanation for the scars, especially the horrific ones that you are going to see now that summer is on the way. Furthermore, the knowledge of what causes the scars has implications for everyone.

[BTW my parents' generation does have scars on their upper arms from inoculation so the vaccination program must have stopped around 1970 in Canada. I was born in that year. I don't have the scar.]

The vaccination in question is that of small pox. I think the common assumption is that the scarring is due to vaccinations gone wrong. This is true. Regarding the administration of the vaccine (the origins of the word vaccine actually comes from 'vacca' or cow which is where the first vaccine was derived from: a cow virus):

"Using a bifurcated needle, the dermis in the region of the deltoid of the non-dominant arm is injected multiple times with the vaccine, with the intention of limiting the territory to a 5-mm circle."

This good outcome is called a hypertrophic scar. It stays within the original wounded area and may reduce over time. Of course, best intentions don't always turn out that way. The bad outcomes are called keloids.

"A keloid is a special type of scar which results in an overgrowth of tissue at the site of a healed skin injury. Keloids are firm, rubbery lesions or shiny, fibrous nodules and can vary from pink to flesh-colored or red to dark brown in color." (WIKI)

I think the differences between the scars is the pictures above are now clear. The most definitive source of information about this that I was able to find on the net was a letter to the American Academy of Family Physicians.

The letter is a plea to change the location of the vaccination so as to minimize scarring. The small pox vaccination is done on the deltoid for everyone in Taiwan to serve as proof of inoculation. However, as the letter points out:

"The shoulder region, the chest, and the earlobes have long been known to be areas associated with an increased incidence of hypertrophic scarring and keloid formation, especially in patients with darker complexions. An initial recommendation was made to avoid the problem of upper shoulder scarring by lowering the location of vaccine administration to well below the tip of the shoulder." Furthermore "individuals [are] prone to increased scarring because of a genetic predisposition."

So it seems that placement and race genetics may hamper Chinese people's ability to have hypertrophic scars rather than keloids. Thus the high amount of terrible scars on people's arms in Taiwan.

So what is the implication for those of us who are lucky not to have a scar at all? Well, terrorism. Remember all that talk about biological weapons in Iraq and small pox? Well, plans have been made to vaccinate you if there were another outbreak of small pox used as a biological weapon and although:

"[Some] point out that mass vaccinations would probably not be needed to counter a bioterrorist attack if many millions of doses of the current (possibly improved) vaccine could be delivered to victims within several days of exposure (the vaccine is effective to that point). This, along with vaccinations of so-called first-responders, is the current plan of action being devised by the United States Department of Homeland Security and FEMA." (WIKI)

This probably goes for a few other nations too. Let's hope it never has to go that far... I don't want the chance of getting an ugly keloid on my deltoid!

So here's the million dollar question... If we stopped vaccinating for small pox years ago then why does Taiwan still do it? Can anyone answer this for me?
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