ok, I checked the archives–I now know I don’t want to get smallpox. I was vaccinated LONG AGO. When the shots become available again, can I assume that since I survived the first vaccination with no unpleasant surprises, I am not at risk from adverse reactions upon re-vaccination?
I don’t think you can conclude that with absolute certainty, but it seems very unlikely. Even if the first innoculation had sensitized you to a dangerous extent, that acquired allergy would have faded by now, along with the immunity. Any native sensitivity would have been displayed at the original innoculation.
However, if they’re still using a live-virus vaccine, you still stand a chance of getting sick.
OK, let’s review what the smallpox vaccine is and isn’t.
First of all, it isn’t smallpox. It’s a related but much less lethal virus known as vaccinia or cowpox. At present, all “smallpox vaccine” is live virus. Essentially, you’re delibrately getting a little illness to prevent a much bigger illness.
“Allergy” is sub-category of "bad reactions. When Nametag mentions “if the first innoculation had sensitized you to a dangerous extent, that acquired allergy would have faded by now, along with the immunity” he is talking about an allergic reaction. Contrary to what is implied, you can have a completely uneventful first innoculation, and at the second display a severe (even lethal) allergic reaction although this is extremely rare, even among folks with other allergies. If you did have a “bad reaction” to a prior innoculation you may or may not have one at the next - not all bad reactions are allergies. Nor do all allergies fade with time. It is entirely possible for the smallpox resistance to have worn off but the allergy to remain.
There is also the matter of being allergic to cowpox vs. being allergic to cows, which is what the cowpox is cultured in/on - bovines. If you are allergic to cows you will likely have a very bad reaction to the innoculation, not because of the cowpox but because you will be exposed to cow protein. In theory, if the vaccine could be cultured on, say, zebras and you’re not allergic to zebras then it might be safe to vaccinate you, since there would be no offending cow proteins for your immune system to get upset over.
But let’s get back to the vaccine itself. As I said, cowpox is a live-virus when used to innoculate a person against smallpox. You are going to get sick. That is sort of the purpose of the whole exercise. However, almost all the time it is a very minor illness. Your arm will hurt, you will likely run a low fever for a few days, but most folks who have had the vaccine as adults (and thus could articulate their reactions) were able to function, go to work, do chores, etc even during those few days they didn’t feel great. Certainly, in comparison to getting actual smallpox it was a great bargain.
Now, let’s talk bad reactions. There are some people who just shouldn’t get this vaccine. Anyone with HIV, for example, or post-organ transplant, or anything that depresses the immune system (such as cancer chemotherapy). A malfunctioning immune system may not be able to deal with the cowpox virus, which can be fatal in these instances.
An active herpes infection - which you might have acquired since a childhood vaccination - is also not a good mix with cowpox. “Herpes infections” include both the genital herpes and the oral herpes also known as “cold sores”, chicken pox, and shingles. I’m pretty sure that in such cases you need to wait for the herpes virus to go into remission prior to smallpox vaccinations.
Anyone with active eczema should not have a smallpox vaccination. It can be deadly when combined with eczema (it sort of eats your skin. Yuuuuuck). Presumably, this means active eczema, since I had both eczema off and on as a child and a smallpox vaccination, which I survived quite well. I think psoriasis might be a contra-indication as well, but truthfully my recollection on that is fuzzy.
And some folks just plain get sicker than expected. This category includes brain and spinal cord swelling (can lead to coma or death) or the little virus spreads beyond the vaccination site, leading to scars in multiple locations. If these secondary infections involve the eye it can lead to blindness. If massive may require plastic and reconstructive surgery.
Gee, doesn’t a smallpox vaccination sound like fun?
Seriously, though, the above reactions ARE rare, and since many of the risk factors can be identified ahead of time, you can self-eliminate if you’re at high risk for many complications. Tens, if not hundreds, of millions of people have had smallpox vaccinations, felt grotty for a few days, then went on with their lives as if nothing had happened.
Because there are real risks, because the odds of a bad reaction with this vaccine are higher than with almost any other vaccine currently in use, and the bad reactions can be SO bad, and because this disease no longer exists in the “wild”, health authorities are reluctant to advocate mass vaccinations. However, if an outbreak DOES occur, by all means, DO get vaccinated because you are much, much less likely to become seriously ill or die from a smallpox vaccination than from smallpox itself. It’s a matter of weighing the odds of a given situation.
If there is no outbreak, but vaccine is made available for your use, I’d advise you do some research on your own, perhaps consult with a doctor beforehand, and make your own choice. Someone who is a nurse or doctor or paramedic, who might be a “first responder” in the event of an outbreak, might have professional reasons to consider vaccination in advance.