Review of Flu and Common Cold 1924
The specific causes of influenza and common cold were not known and in the early 20th century numerous “transmission” experiments were conducted to see if "filter passing organisms" could be the cause. One of those was by Robertson and Groves who took nasal secretions of 11 people sick with the common cold. They inoculated 100 healthy people with these secretions and were unable to reproduce (or “transmit”) the illness to the healthy subjects.
The latest observers to express their opinion in the negative are Robertson and Groves who reported in April, 1924, the following:
Results of the 100 human inoculations are: Positive for bronchitis, 1 case (1 per cent) ; coryza, 1 case (1 per cent) ; influenza, 1 case (1 per cent) ; laryngitis, 2 cases (2 per cent). They were 95 negative cases (95 per cent) free from any respiratory infection following inoculation.
Twelve days allowed for incubation.
In any groups of persons selected at random during a time when an epidemic of colds is present a certain small percentage will develop upper respiratory infection within a period of 12 days. This we believe, fully explains the cases which we recorded as positive.
In the series of experiments nasal secretions were secured from 11 persons suffering with acute uncomplicated corzya. After being diluted and passed through a Berkefiled filter these secretions were sprayed onto the nasal mucosa of a 100 volunteers.
The experiments presented no convincing evidence indicative of a filter-passing organism as the exciting factor in acute corzya. We believe the cases recorded as positive to be the result of factors independent of the inoculations.