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New B-type influenza virus strains may reach US this winter
Physicians should be completing their last immunizations for the 1973-1974 influenza season by now.That is the recommendation of the Public Health Service's Advisory Committee on Immunization Practices that was first made nearly six months ago.Exactly a year ago, the first major outbreak of a "moderately distinctive but not altogether new" variant of the "Hong Kong flu" virus (A/England/42/72) was reported among a United States civilian population in Baltimore. This "London Type A" influenza virus spread through much —but not all—of the continental United States during the next four months, while type B influenza was minimal. During this period, pneumonia and influenza caused at least 2,200 more deaths than normally would have been expected.In view of that history, this season's bivalent influenza vaccine contains, in adult doses, at least 1,000 chick cell agglutinating units of antigen. Seven hundred units are
Medical News. JAMA. 1973;226(9):1063–1072. doi:10.1001/jama.1973.03230090001001