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For many vaccines the amount of antibodies induced has a positive correlation with the likelihood of clinical protection from disease. Mean antibody level is therefore frequently used as a serological surrogate endpoint for vaccine efficacy. In addition, a dichotomous surrogate endpoint is often defined: seroprotection. We explore the relationship between mean antibody level, seroprotection and clinical...
HI titers measure anti-HA antibody concentrations in sera. By the way they are defined standard titers underestimate the true amounts of antibody. A new definition is proposed, the mid-value definition. Under mild conditions mid-value titers are on average closer to the true value than standard titers.
In a well-know CHMP Note for Guidance criteria are given for evaluation the results of annual-update studies. Now and then it sometimes is suggested that these criteria can be improved by the use of confidence intervals. Here it is argued that this is based on a misinterpretation of what confidence intervals are. These intervals require that subjects are chosen at random from a population. In influenza...
The standard test for anti-haemagglutinin antibody titration is the haemagglutination inhibition (HI) test. The HI titre is defined as the dilution factor of the highest dilution that still completely inhibits haemagglutination. If the highest dilution tested (1:2560) still completely inhibits haemagglutination, an HI titre value of 2560 is assigned. Logarithmically transformed HI titres tend to be...
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