Virulence for man of a human influenza-A virus antigenically similar to "classical" swine viruses.

The newly isolated human influenza-A strain containing swine antigens isolated in New Jersey, U.S.A., was inoculated into six volunteers. Clinical reactions were mild although all volunteers were infected. The longest period for which the virus was excreted was 8 days and the shortest 3 days. In its virulence for man the New Jersey strain was intermediate between a human and animal virus, and was quite clearly more virulent than known swine viruses. It seems possible that the outbreak in the U.S.A. was an isolated event and that the virus will not become established in man.