St. Louis University researchers recently conducted a study in which the efficacy of a vaccine with three strains was compared to that of a quadrivalent vaccine. The quadrivalent vaccine was found to be more effective than the trivalent with regards to influenza, especially when administered intradermally. The quadrivalent vaccine had two A strains and two B strains, whilst the trivalent had the same two A strains and just one B strain.
The study was conducted on 3355 volunteers between the ages of 18 to 64; those that received the vaccine with the four strains showed a better antibody response overall. They found that by adding the fourth strain, the chances that the vaccine will match the circulating flu strain are increased.
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