031 - The Value of Mixed Vaccines in the Prevention of the Common Cold

You can probably guess from the title what the conclusion of this study was.

That said, it was actually a very good study, at least for the time; future studies claimed that this one might've been the first real clinical trial. It was in the vein of post 026, using a vaccine made of multiple types of killed bacteria to immunize against the common cold.

This one took place at the University of Manchester, and contained four main groups of subjects: those that volunteered to be randomly assigned either to vaccination group or control group, those that volunteered to be vaccinated, and those that volunteered to be controls. So about half the subjects were randomized and the others weren't. This didn't make much difference in the end though. The randomized groups, at least, were about evenly matched in sex and time since last cold.

The vaccine was made with several different types of bacteria commonly found in respiratory infections, including pneumococcus. Three injections were given, a week apart. Most reactions, if any, were trivial; some had an induration lasting a couple weeks, and one had a swelling that became an ulcer that healed slowly. But nothing very serious.

However, considering the results, the risks probably weren't worthwhile: the vaccinated groups got sick more than the controls. It wasn't a significant difference, 1.47 colds per person for vaccinated compared to 1.14 per person for controls, but it was quite clear that the vaccine did not help. Severity of illness was no less for the vaccinated group either. And the pattern was the same for the randomly assigned groups as for those that volunteered for one group or the other.

The scientists kept good records of different things in this study, and considered the possibility of different kinds of bias, so it was a relatively good study overall. There was randomization and group matching and such. Not up to today's standards, of course—it wasn't single- or double-blinded and there wasn't a placebo, for two things—but it was progress.

As a side note, there was a graph of how many colds lasted how long, and most of them were around 7 days long (as expected), though a few were more than 50 days.

Finally, I liked this quote from the article:

"We would add a word of warning with regard to the utter uselessness of the reports of individual patients as evidence of efficient prophylaxis. Among any large population, some persons will experience fewer colds during any particular winter, than they have experienced in previous year. In no department of human reasoning does the argument, post hoc propter hoc hold more absolute sway, than in the lay evaluation of medical procedures."

Always a good thing to remember, regarding conventional medicine or alternative medicine alike.

Citation: Ferguson, F. R., Davey, A. F. C. & Topley, W. W. C. The Value of Mixed Vaccines in the Prevention of the Common Cold. J Hyg (Lond) 26, 98–109 (1927).