Memorable Shot: Smallpox Vaccine Has Lasting Effect (40's-50's Vaccination Still Good)

Science News Magazine ^ | 5-31-2003 | John Travis

[blam]

Week of May 31, 2003; Vol. 163, No. 22

Memorable Shot: Smallpox vaccine has lasting effect

John Travis

The threat that the smallpox virus could be used by terrorists as a biological weapon has become a cornerstone of modern angst. Now, a research team finds reason to assuage some of that anxiety: People vaccinated against smallpox decades ago retain significant antibody and immune-cell responses against the dangerous virus.

"We're finding long-term immunity," says Mark Slifka of Oregon Health and Science University in Beaverton. At last week's meeting of the American Society for Microbiology in Washington, D.C., Slifka and his colleague Erika Hammarlund reported the results of their survey of more than 300 people who had received one or more smallpox vaccinations over the past 75 years.

After a global immunization campaign against smallpox in the 1960s and 1970s, the disease was declared eradicated in 1980, and vaccinations were stopped. Fearful of an attack with the smallpox virus, however, the U.S. government recently began immunizing soldiers and health-care workers who would be the first to respond to an outbreak. Because the vaccine can have serious side effects, a debate has erupted over whether to widely vaccinate the public after an outbreak or just immunize people in the area where the outbreak occurs, a strategy called ring vaccination (SN: 4/5/03, p. 218: Available to subscribers at http://www.sciencenews.org/20030405/bob9.asp).

To inform that decision, researchers have developed computer models that predict how smallpox would spread given a range of factors. One of the biggest sources of uncertainty in such models has been whether people vaccinated decades ago remain immune. An online fact sheet from the Centers for Disease Control and Prevention in Atlanta, for example, declares, "Smallpox vaccination provides high level immunity for 3 to 5 years and decreasing immunity thereafter."

Slifka, Hammarlund, and their colleagues took blood samples from one group of people who had received smallpox vaccinations between 20 and 75 years ago and another group of people who were immunized only recently. Then, in test tube studies, the scientists measured antibody and immune-cell responses to the virus.

The investigators found that more than 90 percent of the people vaccinated decades ago had an antibody response similar to the response of those recently vaccinated. The strength of the immune-cell response did decline with time, but virus-specific immune cells are still found in people vaccinated as long ago as the 1940s.

For Slifka, that finding all but settles the debate about how to respond to a new outbreak. "It would be unlikely that we would need to mass-vaccinate," he concludes. "The ring-vaccination approach would be very effective."

Not everyone agrees. Edward H. Kaplan of Yale University has modeled the spread of smallpox, including scenarios in which 50 percent of the public is already immune. "While [widespread immunity] would certainly reduce the number of deaths, it would still not tip me from recommending post-attack mass vaccination," Kaplan says.

Making public policy on the basis of test-tube studies is a challenge, notes Jeff Frelinger of the University of North Carolina at Chapel Hill, who has documented continued immune responses to the smallpox virus in about a dozen people vaccinated decades ago. "While the long persistence of immune responses suggests resistance, there exist no studies to calibrate the [test-tube] responses measured with protection from smallpox following exposure."

[Ditter]

My sons were born in '63 & '66 & I remember them being vaccinated. My daughter was born in '72. I just can't remember if she was or not. She has no visable scar. Do you suppose I can't remember because I was really really busy? LOL

[McGavin999]

That's what I've been saying all along. Once the body learns how to fight things, it remembers. I had always planned on not getting re-vaccinated because any emergency vaccinations should be given to the most vulnerable. I figured I could count on both my healthy immune system and the fact that I had been vaccinated many, many......many (sigh) years ago.

[Ditter]

What do you mean booster? A smallpox vaccination has no booster. That was your DPT (diptheria, typhoid & whooping cough) , polio etc.

[riri]

hmmm. 1969. Maybe, I did. However, I do not have a scar, so I don't think so.

[lonestar]

I got mine at school--before you were in first grade. That was in Houston.

[LizardQueen]

Then it's recorded wrong or badly on the card - only type of vax mentioned on it is the smallpox, the other lines contain just a scribbled "booster" and the date, which is more recent thn the smallpox so I thought they were smallpox boosters. Bummer, that means my shot is older than I thought.

Lq

[Clinging Bitterly]

I was vaccinated in the '60s. They said then that if it left a scar, it made you immune permanently. I have the mark, and I don't plan on getting another vaccination.

[backhoe]

I was vaccinated in the early 50's. How about you?

Circa 1955... I still would not object to a booster, just to be sure.

[blam]

" (DDT is safe: just ask the professor who ate it for 40 years...) "

Reminds me of a book I read, I think it was titled, The naked Lunch.

[backhoe]

Well, I really wouldn't try eating the stuff, but we did play in the clouds of DDT from the "skeeter truck" when it went by the house- childishly thinking, "bad for bugs, good for me!" It honestly didn't seem to cause any harm to humans- the stuff they spray now stinks, makes the bugs hyperactive, and does not kill them at all.

[Judith Anne]

I was revaccinated at my request in 71 (Hub and I both) for a trip outside the country...neither of ours took, doctor said it was because we were still immune.

It was the third vaccine for both of us, we got them in the early fifties first, then in the 60s. I'd like to know what the smallpox titers are, for the decades after vaccination...

[nopardons]

This article is correct and I've been saying the same thing ( got my answer from a prominant, highly regarded doctor, who happens to be a friend ) when it first cropped up on FR and the virtual hypocondriacs/hysterics were in full throttle. They were dead wrong, I was right, and the hysteric health threads, on FR are not only a damned waste of bandwidth, they are about as useful as lipstick on a pig !

[Alas Babylon!]

I got my last smallpox innoculation in 1979. Lucky me. I was going overseas then in service to my country!

[not-an-ostrich]

Vaccinated in 1946. In fact I have a photo of me at the time with a large bandage on my arm.

[Owen]

Folks, it is probability. If you were vaccinated decades ago, 90% of you are safe. 10% of you are not. If you are vaccinated recently, that 90% number rises towards 100% (never reaching it, of course). The guy in the article who still advocated mass vaccinations is thinking in these terms. 10% of 260 million is 26 million vulnerable people.

But for your individual case, if you got the shot decades ago your odds are pretty good.

[clodkicker]

A question. Would the immunity pass to our children if we had the shot?

[blam]

"A question. Would the immunity pass to our children if we had the shot?"

I don't think so, someone in the know will be by soon and answer your question. (bump)

[pttttt]

If you want to get another one, NIH is having clinical trials. See NIH Seeks Subjects For Smallpox Vaccine Trials.