Which patient-specific factor can affect vaccine responses?

Age is a significant patient-specific factor that can affect vaccine responses. This is due to the differences in immune system development and functionality across various age groups. Infants, children, adults, and the elderly all have varying immune responses based on their age. For instance, infants may have immature immune systems, making them more susceptible to infections and sometimes necessitating specific vaccine schedules to adequately protect them. Conversely, the elderly may have weakened immune responses, which can lead to lower efficacy of vaccines, necessitating higher dosages or adjuvants in some cases.

While factors such as location, gender, and occupation may play a role in determining exposure risk to certain diseases, they do not directly influence the biological response of the immune system to vaccines like age does. Therefore, age is the most crucial factor when considering how well an individual may respond to vaccinations.