From the information in the passage, there is evidence

You would think that the common cold should be easy enough to study, but it is not as easy as it looks. Colds often seem to spread from one person to another, so it is often assumed that the cold must be infectious but there are some puzzling observations which do not fit with this theory. An investigator in Holland examined some eight thousand volunteers from different areas and came to the conclusion that in each group the colds all appeared at the same time. Transfer of infection from case to case could not account for that. Yet at the common cold research unit in Salisbury, the infection theory has been tested out; two series of about two hundred people each were inoculated, one with salt water and the other with secretion from known cold victims. Only one of the salt-water group got a cold compared with seventy-three in the other group.

  In the British Medical Journal the other day, there was a report of a meeting. ‘The Common Cold – Fact and Fancy’, at which one of the speakers reported a study of colds made in Cirencester over the last five years. Three hundred and fifty volunteers had kept diary records of their colds and on an average, each had seven every year with an annual morbidity of seven days. So nearly one-fiftieth of our lives is spent in more or less misery, coughing and sneezing. Some widely held beliefs about the common cold have turned out not to be true. It seems that old people are just as liable to colds as the young. Sailors in isolated weather ships have just as many colds while on board and not in contact with the outside world as when on shore. It is a truism that common illnesses pose more problems than the rare. The rare disease is by comparison much easier to handle. There are not so many cases and all of them have been intensively studied. Someone has read up all the literature about the disease and published a digest of it. There will be more facts and fewer fancies.