Max Hamilton , M.D., F.R.C.P.E. (Psychosomatics, 1955) wrote …

“It is now known that an infection by a virus may remain ‘latent.’ i.e. showing no symptoms, for a remarkably long period, and that the development of symptoms may be related to a change in the resistance of the host, brought about by many different factors, e.g. exposure to cold, infection with another organism, and so on. It is not so improbable now as it might have appeared ten or fifteen years ago that one of such precipitating factors might be emotional stress. There are now many case-records that give much food for thought. In this connexion we may consider a rather old paper by Saul, 1938. He collected data from six psycho-analysts describing fifteen patients, every one of whom had had repeated colds before analysis, and few or none in the three years after their analysis. He describes 9 of them; the colds occurred regularly in situations of frustration of strong unconscious receptive demands associated with more or less repressed rage.”