Vaccines stimulate a person’s immune system to produce immunity to a specific disease, protecting the person from that disease.
They contain weakened or dead disease-causing bacteria or viruses, or even just a few proteins or sugars from its surface.
Once stimulated by the vaccine, our body produces antibodies which will match the invading bacteria.
Some white blood cells also become ‘memory cells’ that remain sensitized and ready to respond to the bacteria if it should it ever enter the body again.
Unlike most medicines, which treat or cure diseases, vaccines prevent them.
Vaccines are usually administered by injection, but some are given orally or even nasally.
Also read: UNICEF to stockpile half a billion syringes for COVID-19 vaccinations
Vaccines do not only protect the immunized, when a sufficient number of individuals in a population are immune to a disease herd immunity is achieved .
Which means the pathogen cannot be spread throughout the population.
According to the World Health Organization there are now vaccines to prevent more than 20 life-threatening diseases including diphtheria, tetanus, pertussis, influenza and measles.
Yet nearly 20 million infants have insufficient access to vaccines each year.
Also read: Vaccine shot ‘painless’, say Covishield trial volunteers
India has the Universal Immunisation Programme which is a vaccine-delivery platform for children and pregnant women, funded by the central government and implemented by State governments.
Although almost all children in India are vaccinated against tuberculosis, and receive their birth dose of polio vaccine, two out of five children do not complete their immunisation programme, according to the ‘Health in India’ report.
Full immunisation means that a child receives a cocktail of eight vaccine doses in the first year of life.
Also read: Very large portion of COVID-19 vaccines likely to be manufactured in India
Globally, innumerable COVID-19 vaccine trials are progressing but availability will be limited at first.
The World Bank has approved $12 billion in financing to help developing countries buy and distribute coronavirus vaccines, tests, and treatments, aiming to support the vaccination of up to one billion people.