Because of the multiple factors controlling host responses to vaccines or to infections, more effective disease control strategies should be developed in an integrated animal health management approach, including prevention, cure, environment control and breeding for improved immunocompetence. The impact of host genetic variation in shaping innate and adaptive immune response is an emerging lever to consider in new vaccination strategies. Indeed, in the same flock, not all birds even vaccinated simultaneously and with the same dose, will respond equally to a vaccine. This study aimed at, 1- utilizing the host genetic variability of the response to Eimeria maxima vaccination of chickens to search for blood biomarkers predictive of vaccine response intensities; then 2- to test the candidate biomarkers in validation populations for another vaccine response, to Newcastle Disease Virus Vaccine (NDV). For the search of biomarkers to E. maxima vaccine, 90 male commercial broilers (Cobb 500) were used. Nine days after vaccination with 100 E. maxima Weybridge strain oocysts at 16d, a subset of 79 birds were challenged with 50,000 parasites of the homologous species/strain. Body weight gain, lesion scores, parasite load and IL-10 serum levels were used to assess birds' responses. Birds were ranked according to their vaccine responses and RNAseq data were produced from blood sampled prior vaccination for 63 birds representing the diversity of responses. For each response phenotype, high and low responders were selected (upper and lower quartiles) and sparse Partial Least Squares-Discriminant Analyses (sPLS-DA) were carried out to identify the best predictive blood biomarkers classifying birds into each group. Finally, 108 candidate genes, predictive with accuracy higher than 97% for all vaccine responses, were selected. A custom OpenArray for highthroughput RTqPCR assays was then design to test the candidate biomarkers in validation populations. First test was performed on a population of White Leghorn selected birds displaying a large variability of response to NDV vaccine. This is a proof of concept that blood before vaccination can be used as a relevant source of biomarkers predictive of vaccine responses. Future researches, combining genetic variability of response to vaccine and disease and novel vaccines, pave the way for better and more efficient vaccination through "precision vaccination" and "personalized health management".