025 - Mills-Reincke Phenomenon and Typhoid Control by Vaccine

This article wasn't really about the safety or effectiveness of a particular vaccine, but it does relate to the question of whether it's worthwhile to vaccinate the whole population (and also another concern people sometimes raise), so I thought it was interesting.

First off, a definition: The Mills-Reincke phenomenon (and similarly, Hazen's theorem) was, hypothetically at least, the idea that typhoid fever could be prevented by cleaning up a population's water supply (since typhoid is spread through fecal contamination of water and such), and that for every typhoid death prevented by cleaning the water supply, several deaths from other causes would also be prevented by the same sanitation efforts. Presumably these other deaths might be caused by other water-borne infectious agents, or a general weakening due to any kind of water-borne infection.

At the time, public health officials in the US were considering vaccinating the population, or at least certain parts of it, against typhoid. The author of this paper warns against that, saying that this approach may mask the true problem (contamination of the water supply). Instead, water should be made as clean as possible, and typhoid cases may be used as an indication of contamination.

To support this position, he presents evidence from Alpena, Michigan, a town situated near Lake Huron. This town took its water from the lake and also dumped its sewage therein, and not surprisingly suffered from typhoid fever. But in the years between 1900 and 1918, a few changes occurred in the water supply: first, in 1907, the water intake was moved to a more polluted section of the lake; then in 1915, improvements were made in the sterilization of the water.

As a result of these changes, the annual mortality rates (that is, number of people dying each year) from typhoid or all causes changed. The average mortality from typhoid between 1908 and 1915 was higher by about 36 deaths per 100,000 people than the average between 1900 and 1907; in contrast, the mortality from all causes was higher by almost 150 deaths per 100,000. So for every one extra typhoid death, there were about 3 more deaths from other causes, in line with Hazen's theorem.

And when the water was cleaned better in 1915, there were about 4 fewer non-typhoid deaths for each one typhoid death prevented, though the data for this period is limited to only two years (1916 to 1917; the 1918 flu epidemic kinda skewed the all-cause mortality data for that year).

So it does seem that, given a choice between vaccinating against typhoid vs. cleaning up the water supply, the latter is the better option. Not surprising. Lest anyone conclude that this makes vaccines less valuable, though, the average mortality from typhoid between 1916 and 1918 was still about 13 deaths per 100,000 people, so there was still room for vaccinating to be useful. At least back then. Since we don't really do typhoid vaccination much in the US today, I suppose it turned out not to be helpful. This study doesn't say much about any other kind of vaccine though.

Citation: McGee, H. G. Mills-Reincke Phenomenon and Typhoid Control by Vaccine. Am J Public Health (N Y) 10, 585–587 (1920).