In another article1 I referred to the relative immunity which develops in children from the seventh to the ninth year. While this conception is common among physicians, I do not know of any study which shows this in plain figures.
I have gone over my records for six years (1913-1918) and tabulated the age of the children who were seen suffering from acute disorder of the respiratory tract. This series embraced the following diseases: Coryza, adenoiditis, otitis media, pharyngitis, tonsillitis, laryngitis, tracheitis, bronchitis, bronchiolitis, bronchopneumonia and pneumonia; cases of grippe, colds and coughs were also included. Cases of Spanish influenza occurring during the epidemic of 1918-1919, were excluded.
It should be remembered, however, that this does not include all the cases occurring in families. Many mild cases and so many "colds" in older children do not produce sufficient anxiety to the parent so that a physician's advice is sought.
ZAHORSKY J. THE RESISTANCE TO ACUTE DISEASE OF THE RESPIRATORY TRACT IN CHILDREN. Am J Dis Child. 1921;21(2):183-186. doi:10.1001/archpedi.1921.01910320080010