Our obsession with geographic eponyms for a disease of worldwide distribution is best illustrated by Russian, or later red influenza or red flu, which first came to attention in November 1977, in the Soviet Union. However, it was later reported as having first occurred in northeastern China in May of that year.

It quickly became apparent that this rapidly spreading epidemic was almost entirely restricted to persons <25 years of age and that, in general, the disease was mild, although characterized by typical symptoms of influenza. The age distribution was attributed to the absence of H1N1 viruses in humans after 1957 and the subsequent successive dominance of the H2N2 and then the H3N2 subtypes.

When antigenic and molecular characterization of this virus showed that both the HA and NA antigens were remarkably similar to those of the 1950s, this finding had profound implications. Where had the virus been that it was relatively unchanged after 20 years? If serially (and cryptically) transmitted in humans, antigenic drift should have led to many changes after 2 decades. Reactivation of a long dormant infection was a possibility, but the idea conflicts with all we know of the biology of the virus in which a latent phase has not been found.

Had the virus been in a deep freeze? This was a disturbing thought because it implied concealed experimentation with live virus, perhaps in a vaccine. Delayed mutation and consequent evolutionary stasis in an animal host are not unreasonable, but in what host? And if a full-blown epidemic did originate, it would be the first to do so in the history of modern virology, and a situation quite unlike the contemporary situation with H5N1 and its protracted epizootic phase. Thus, the final answer to the 1977 epidemic is not yet known.