First came the recommendation for administration of one dose of measles vaccine, the prediction generally being it would last a lifetime. (Never mind that a lifetime of measles vaccine use had not and has not yet occurred.)
Next came the recommendation that we get a booster shot.
(According to the textbook "Vaccines" and the American Academy of Pediatrics and others, the reason for the second dose is to catch the 5% or so for whom the vaccine never worked in the first place [primary vaccine failure], and not because of waning immunity [secondary vaccine failure]. However, this position is a puzzling one to take because a) waiting until age 4-6 or 10-12 to give the second dose doesn't make sense in those cases where the vaccine is thought to have never worked, and 2) there appears to be enough evidence of waning immunity to consider it a genuine risk. Thus an argument can be made that it was the fact that the prediction for long-term immunity had been premature, as much as any problems associated with primary failure of the vaccine, that led to the new recommendation.)
At any rate, we are now vaccinating the approximately 95%, who allegedly got lifelong immunity immunity from the first dose, a second time. And at the same time are still being told the vaccine probably lasts a lifetime.
Meanwhile, predictions about when and if measles eradication will occur continue to be revised.
So far, so "good". You get two measles shots, you're (extra) protected for life, even if measles isn't ever eradicated. Worse case scenario, you get vaccinated again. No problémo.
There are actually serious problémos with this scenario, however. But first we need to understand a bit about measles epidemiology, before it will make sense.
When measles and other infectious diseases first hit a "virgin" population, almost everyone gets sick. In the case of measles, many infants and adults, for whom measles can frequently be a serious disease, die, while most otherwise healthy children, for whom it usually is not, survive. From that point on, almost everyone who had the measles has life-long immunity (until fairly recently, conventional wisdom being that immunity automatically is lifelong). Mothers go on to pass on immunity transplacentally to their infants, protecting them during that dangerous infancy period. And children grow into adulthood and ordinarily do not experience it again. (For an interesting, contrary explanation for the high death rates in "virgin populations", click here.)
Nature has provided a pretty good system, one that usually works quite well, at least in developed nations, where living conditions and overall health are generally good.
One of the first signs of trouble was when it was discovered that measles-vaccinated moms do not protect their infants the way moms who had the measles do. To compound the problem, whenever there was maternal protection, it interfered with the effectiveness of the measles vaccine. (The disaster in Africa when trying to deal with maternal antibodies was discussed in an earlier Scandals.)
Now we find that measles may not be able to be eradicated or controlled on a long-term basis, the biggest impediment possibly being that it circulates among the vaccinated, boosting vaccine-induced immunity and causing mild or subclinical cases of the disease. All of which means that if the vaccine is not life-long, we are probably looking at adults getting the measles, unless they are (repeatedly?) vaccinated.
But what if repeated vaccination is not safe?
And what if re-vaccination does not work? There is clearly evidence that it may not. Even Dr. Samuel Katz, one of the developers of the measles vaccine, and his coauthors admit as much in their chapter on measles in the textbook "Vaccines", when they write, “Boosting of antibody titers appears to be transient, with several investigators finding decay of antibody levels to the pre-revaccination level within months to years”.
So instead of a world free of measles with an extra measure of vaccine protection, we may be looking at infants and adults getting and dying from the disease. And it would seem that the only way to avoid such a disaster, given current knowledge of immunity and the measles, is to get the measles as a child (when it is usually quite harmless in developed nations), with repeated exposure to it during one's lifetime.
Just the opposite of what vaccination policy is trying to achieve.
And exactly what Mother Nature was doing in the first place. Maybe Mother Nature really does, at least sometimes, know best.