« Bivalent influenza vaccine, incorporating a type A and a type B strain in a single vaccine, is now available from many manufacturers. The strains included are those considered most likely to infect patients this winter. As in the past, there is no certainty that the vaccine will be effective since new strains may continue to emerge. To assure protection of high-risk patients before the usual influenza season, the vaccine should be given by early November »
The Medical Letter on Drugs and Therapeutics, 56 Harrison Street, New Rochelle, N.Y., vol. 16, n° 20 (Issue 410), September 27, 1974