What is vaccination or a vaccine?
The process of stimulating one’s immune system against disease causing micro-organisms by introducing killed or weakened micro-organisms into one’s body is called vaccination.
In common speech, the terms vaccination and immunization can be used interchangeably.
Basically speaking, an infection is a bit like a war between these micro-organisms that cause diseases, and the body’s immune system, trying to prevent the said disease.
Vaccination prepares the body’s immune system for future attacks by micro-organisms by exposing them to a killed or weakened micro-organism, so that the immune system can remember this micro-organism at a later date, and act swiftly and effectively to wipe the micro-organisms out, when they get into the body, before clinical disease develops.
A child’s immune system is not as developed as an adult’s is. By the time a person becomes an adult, their immune system has faced multiple challenges in the form of micro-organisms. Consequently, they are better prepared for future infections by similar micro-organisms.
Children, on the other hand, have faced barely any such challenges, and hence, are not as prepared to deal with infections as well as adults are. That is why a child’s immune system needs to be stimulated against specific micro-organisms (depending on the prevalence and severity of the diseases these organisms cause).
Children are not the only ones who need vaccines, though. Adults require them too. Indeed, there is a separate vaccination schedule for adults, drawn up by the World Health Organization and the Centre for Disease Control.
Vaccination in adults is influenced by age, lifestyle, travel plans, high-risk conditions, etc.
Causes for immunization of adults include failure of protective efficacy of childhood vaccines in adults, travel to areas where specific, uncommon diseases are prevalent, to protect children from diseases (for example, people in contact with children on a regular basis can transmit infections to the children), to protect health-care professionals, to protect individuals at high risk for acquiring a particular disease (immunocompromised individuals), new strains of prevalent micro-organisms (for example, the influenza vaccines are revised every 6 months – 1 year) etc.
What is a vaccination schedule?
A vaccination schedule is a schedule made by international health-related agencies, like the WHO, and the CDC, and suitably modified by national health agencies, like the Indian Academy of Pediatrics (to address specific diseases prevalent in a nation).
It is a recommendation that specifies what vaccinations are to be given, and at what age.
The latest IAP recommendations can be found here.
Adult vaccination schedules can be found here.
What are the possible adverse effects of administering a vaccine?
The first thing to be understood here is that adverse effects, other than minor and completely harmless symptoms like a fever, and a local rash, are quite rare.
Vaccines, like any medicine, can cause allergic reactions in the persons they are administered to, but the occurrence of these, also, is quite rare.
For a comprehensive list of vaccine adverse effects, click here.