Indications from intensive clinical and laboratory observations of 23 male and 23 female children under age 19 were as follows: (1) Rubella may occur without rash in a significant proportion of children. (2) Posterior auricular or occipital adenopathy may be indicative of rubella without rash. (3) Children may be infectious several days before and after clinical disease. (4) Throat swabs for virus isolation should be obtained at or near the onset of rash. (Additional confirmation can be provided by antibody determinations with paired serum specimens when the first specimen is obtained near the onset of symptoms.) (5) "Rubella with nodes only" may be difficult to confirm by virus isolation studies and is probably best identified by serum titer changes, the first serum specimen being taken near th onset of symptoms or at the time of known exposure.
Sever JL, Brody JA, Schiff GM, McAlister R, Cutting R. Rubella Epidemic on St. Paul Island in the Pribilofs, 1963II. Clinical and Laboratory Findings for the Intensive Study Population. JAMA. 1965;191(8):624-626. doi:10.1001/jama.1965.03080080014003