Use of an inhibitor-resistant live attenuated influenza vaccine in normal and asthmatic adults

Abstract

The efficacy of a monovalent live attenuated influenza A (H3N2) vaccine (an inhibitor-resistant recombinant strain named "Alice") and of a bivalent vaccine composed of "Alice" and influenza B strain R75 (also inhibitor-resistant), was tested in healthy and asthmatic adults. Two intranasal doses of the monovalent "Alice" vaccine were given to 95 healthy adults in the winter of 1973-74. Ninety-three % of 68 subjects with initial serum hemagglutination (HI) titers of less than or equal to 1:40 had a significant (4-fold or greater) antibody increase in post-vaccination sera. Overall, 77% of the vaccinees had significant antibody rises. Two doses of the bivalent (A/B) vaccine were given to 53 healthy adults in the winter of 1974-75. Eighty-two % of 34 subjects with initial HI titers of less than or equal to 1:40 had 4-fold or greater antibody rises to influenza A, and overall 57% of the vaccinees responded. The B component of the bivalent vaccine was less effective; only 56% of persons with initial HI titers of less than or equal to 1:40, and 28% of all vaccinees had significant antibody rises. Both tf asthmatics who received "Alice" and one of 10 (10%) who received the bivalent vaccine had serologic responses to influenza A. None of the asthmatics responded to the B component of the bivalent vaccine. Analysis of the incidence of febrile respiratory illness during an influenza outbreak in the winter of 1974-75 revealed no differences in the attack rates of placebos and vaccines. In conclusion, both the "Alice" and bivalnet (A/B) vaccines were effective in eliciting serologic responses to influenza A in healthy persons. They were less effective in asthmatics. The lack of protection observed may have been due to the onset of influenza before the vaccine could take effect or to the failure of the vaccine itself.