ANDREWES 



lems which may or may not turn out to be one and the same prob- 

 lem: 1) Does chilling really set off a cold infection and if so how? 

 2) Why are colds commoner in winter than in summer? In other 

 words, is the seasonal prevalence of colds simply due to a sum- 

 mation of the effect of chilling on individuals ? At the moment there 

 is good scientific evidence that colds are in fact commoner in winter. 

 Evidence as to the effect on the individual is more doubtful. 



Cold and Colds in Individuals 



Many people are quite confident that chilling will bring on a cold 

 in them, and they nearly all say that this can happen within an hour 

 or two. A friend of mine has to take time off when she wants her 

 hair washed, as it must be dried immediately and properly, other- 

 wise she "invariably gets a cold". We have offered to test this ex- 

 perimentally but have met with no co-operation. 



Experiments were conducted at the Common Cold Research Unit 

 at Salisbury to test the effects of chilling. In this unit, volunteers 

 come for ten days at a time, having offered their services as "human 

 guinea-pigs". They are kept isolated, usually in pairs, and appropri- 

 ate precautions are taken so that there is no subjective bias in de- 

 ciding whether or not our experimental procedures have given them 

 a cold. In an experiment several years ago, we took three groups of 

 six volunteers (Andrewes, 1950). The three pairs in one group were 

 given diluted virus, which was expected to produce only a few colds. 

 Another six were soaked in hot baths and then made to stand, un- 

 dried, in their bathing dresses in a draughty corridor for 30 min- 

 utes. After that, they wore wet socks for some hours. A third group 

 of six received the dilute virus plus the chilling treatment. Chilling 

 alone produced no colds. The "Virus alone" group got two colds, 

 while the group with virus plus chilling developed four colds. Inter- 

 esting, but not statistically significant. We repeated the experiment 

 and again chilling albne did nothir^. But in the other two groups the 

 result was reversed; there were fewer colds with chilling than 

 without it. In a third experiment our volunteers went for a walk in 

 the rain; on returning rather cold and tired, they found that we had 

 turned off the heat in their quarters. They were treated in three 

 groups as before, and, as in the second test, chilling was not seen to 



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