Update: This post may be confusing because of differences between measles cases (which didn’t drop until vaccination) and measles deaths (which did drop dramatically before vaccination was introduced).  I’ve written much more about the drop in measles deaths, starting here: Measles Week, Part I.

There’s a claim running around the anti-vaccination circles that measles vaccination didn’t do anything because the disease had already dropped by 95% (or 98%) before vaccination was introduced.  That claim is false, of course, and I don’t really expect that debunking it will make any difference, but here it is anyway.

I’m not going to dignifiy the claim with a link.  The author shows a chart with measles incidence dramatically dropping in the early 1900s, and offers a list of references for the chart.  That chart is a flat lie; the references he cites don’t show numbers that bear any relation to the chart he has made up.  I encourage anyone who sees that to check out the references he links — clearly, he’s assuming that people are gullible enough to believe his claim without checking.  Also, of course, I encourage people to check my data.  I’ve taken my numbers from publically-accessible source (thanks to Google Books) and they’re from publications that preceded the vaccine, so there can’t be any claim that the numbers were manipulated by vaccine propnents.  (Unless, of course, the international vaccine conspiracy also has time machines and a vast transdimensional publishing and replacement arm.)

The post-vaccine data I’ve already shown, and I’ll repeat it here.  This is measles in the US, after 1950. (Click for a larger version.) You can easily see where the vaccine was introduced.

Measles cases and deaths after 1950
Measles incidence and deaths in the USA, after 1950

The anti-vaccine claim is that by 1950 measles had already dropped by 95%.  But public health data are available back to at least 1912, and there’s no support for that claim.  Here are the data from the US census (PDF link; measles incidence, expressed as rate per 100,000 population):

US Measles cases, 1912 on
Measles cases in the US, 1912-1997

The specific antivaccine claim is made for the UK.  Fortunately, again, death rates for England and Wales are well documented back into the 19th century.  Here’s what happened to death rates for measles from 1838 to 1937 in the UK (pre-vaccine, obviously).  This is taken from the Annual report of the Registrar-General for England and Wales, Volume 70 By Great Britain. General Register Office (the data up to 1890), from the Parliamentary papers, Volume 13 By Great Britain. Parliament. House of Commons (to 1920), and the 1937 data are from a text entitled “Anomalies and curiosities of medicine” By George Milbry Gould.  (I believe measles stopped being a reportable disease in the UK in 1921, and that’s why the Parliamentary reports stopped including it.)

Measles deaths in England and Wales, 1838-1937
Measles deaths in the UK, 1838-1937

Obviously, there’s no 95% drop. Measles deaths were pretty much constant for over 100 years, until the vaccine was introduced. (EDIT: This is wrong. I meant to write “measles incidence has been pretty much constant … ” not death.  Measles death rate did in fact drop, in some places rather markedly, in the first 50 years of the 20th century (see my long answer to Peter in the comments below for reasons).  The extent of the reduction in death rate (ie. frequency of deaths per case of measles) was very dependent on region — today it’s still 1900-level or so in third-world countries, for example — and depended heavily on nutrition and sanitation.  But the death rate had pretty much plateaued by the early 1950s, and it wasn’t until vaccination spectacularly reduced the incidence and took the deaths away with that.  Nevertheless the death rate drop was nowhere near the 95% claimed by antivaccine loons, as the charts here show.  Check the original sources.)

One important point is that measles is very much an epidemic disease.  It sweeps across a country (in standing waves that originate from cities), and then drops drastically until a new population of susceptible children are born.  That means if you want to fake your data you could draw from peaks and valleys of an epidemic and make it show whatever you want.  Here’s a more detailed illustration of measles — weekly number of cases — in England and Wales (from Benjamin Bolker at hte University of Florida, who compiled these from public reports):

Weekly measles cases 1945-1965
Weekly measles cases in England and Wales

As I say, I don’t really expect this to convince the loons, but I know there are lots of people who are not loons, but who may be puzzled (or fooled) by the loons’ lies.  Don’t take anyone’s word; check the original references.