Immunization is the process by which a person attains immunity or resistance against infectious diseases through vaccinations. A vaccine is a suspension of dead or weakened disease-producing cells (antigen). Vaccination is the process of administering the vaccine into your body. These inactivated cells stimulate your body's immune system. Once vaccinated, your immune system remembers that particular antigen and can combat it again later in your life.
Immunizations are important for children as well as grownups, but the prevalence and complications from vaccine-preventable diseases remain fairly large in adults. Several national agencies have formulated detailed guidelines for comprehensive immunization in adults. Some of the recommended adult vaccines include measles-mumps-rubella (MMR), tetanus-diphtheria-pertussis (Tdap), influenza, pneumococcal, hepatitis A, hepatitis B, varicella and zoster, and human papilloma virus vaccines.
Travelers are at a greater risk for contracting infectious diseases. Vaccinations must be personalized with respect to the traveller's vaccination history, the country to be visited, the type and duration of travel, and the time left for departure. A travel medicine clinic has to be consulted at least 2 to 3 months in advance to allow adequate time to optimize the immunization schedules. Some of the recommended vaccinations for travellers include typhoid, rabies, meningococcal disease, Japanese encephalitis, influenza, hepatitis B, hepatitis A, cholera, Bacille Calmette-Guerin (BCG), yellow fever, tetanus and diphtheria, poliomyelitis, pertussis, and measles-mumps-rubella.
Immunocompromised and pregnant people are, in general, not recommended for live vaccines such as oral typhoid, yellow fever, MMR, varicella, and BCG. Your doctor will be the best person to address your concerns and make further recommendations.