Host factors and vaccine efficacy: Implications for COVID‐19 vaccines.

The efficacy of the vaccines varies between individuals and populations. The immunogenicity of the vaccine is influenced by various factors, including host factors. Previous studies have shown that host factors affect the effectiveness of vaccines, which may be true about COVID‐19 vaccines. In this review, we evaluate the possible association of host factors with vaccine efficacy with a special focus on COVID‐19 vaccines. Highlights: In general, immunosenescence, inflammaging, poor diet, diversity and composition of gut microbiota, and high prevalence of comorbidities are associated with lower vaccine responses in aged people.Immune responses vary between two sexes, which can lead to sex disparities in vaccine responses.Vaccines are less effective in low‐ and middle‐income countries compare to high‐income countries, but malnutrition can contribute.Association between individual microbiota composition and vaccination response has been reported. [ABSTRACT FROM AUTHOR]