[Answered]Explain how vaccines work? Discuss the significance of vaccination and mention various challenges regarding vaccination in India.

A vaccine is a biological preparation that improves immunity to a particular disease. A vaccine typically contains an agent that resembles a disease-causing microorganism, and is often made from weakened or killed forms of the microbe, its toxins or one of its surface proteins. Vaccines are like a training course for the immune system. They prepare the body to fight disease without exposing it to disease symptoms.

How does vaccination work?

1. Our immune system is composed of various types of cells. These cells defend us against invaders and remove harmful pathogens. Vaccination works by teaching our immune system how to recognise new diseases.
2. Vaccines stimulate our bodies to make antibodies against antigens of pathogens. It also teaches the immune system to remember the antigens that cause infection, which leads to a faster response to the same disease in the future.
3. In simple terms, vaccines work by exposing a person to a safer version of a disease. While the body responds to the vaccine, it builds an adaptive immune system, which helps the body to fight off the actual infection in the future.
4. When foreign invaders such as bacteria or viruses enter the body, immune cells called lymphocytes respond by producing antibodies, which are protein molecules. These antibodies fight the invader known as an antigen and protect against further infection.
5. After the threat has passed, many of the antibodies will break down, but immune cells called memory cells remain in the body. When the body encounters that antigen again, the memory cells produce antibodies fast and kill the harmful micro-organism.

Significance of Vaccination:

1. According to WHO, vaccination prevents between two-three million deaths each year, a figure that will rise by another 1.5 million if vaccine coverage improves.
2. Vaccination protects children from serious illness and complications of vaccine-preventable diseases which can include amputation of an arm or leg, paralysis of limbs, hearing loss, convulsions, brain damage, and death. A study in 2017 that looked at flu seasons between 2010 and 2014 found that vaccination reduced flu-associated deaths by 65% among healthy children.
3. The vaccine can also prevent hospitalisations (thereby it can check out of pocket expenditure), reduce the severity of illness and prevent severe, life-threatening complications in children.
4. Efficacious vaccines not only protect the immunised, but can also reduce disease among un-immunised individuals in the community through “indirect effects” or “herd protection”. Because of herd protection, some diseases can be eliminated without 100% immunisation coverage.
5. By reducing the need for antibiotics, vaccines may reduce the prevalence and hinder the development of resistant strains, thereby preventing antibiotic resistance.
6. Vaccines can increase life expectancy by protecting against diseases against which one would not expect benefit.
7. With improvements in infant and child mortality, women tend to opt for fewer children as the need to have many children to ensure that some will reach adulthood is reduced. This has significant health, educational, social and economic benefits.
8. Poor health has been shown to stunt economic growth while good health can promote social development and economic growth. Health is fundamental to economic growth for developing countries and vaccinations form the bedrock of their public health programmes.

Challenges regarding vaccination in India:

1. Lack of social awareness amongst families for the need of vaccination due to illiteracy and religious beliefs.
2. Inadequate health infrastructure, lack of targeted and robust health delivery mechanisms and deficient last mile delivery.
3. Lack of well equipped and trained health care workers.
4. Misconceptions about immunisation mostly among poor and underprivileged about vaccines and their side effects.
5. Vaccines require cold chain infrastructure for storage. Logistical and Infrastructural issues in storage of vaccines hampering it’s penetrability in the rural hinterland.
6. Inadequate labour force and vaccination centres in areas with sparse population.
7. Absence of a monitoring mechanism to ascertain the degree of coverage in every village/block/district.

The benefits of vaccination extend beyond prevention of specific diseases in individuals. They enable a rich, multifaceted harvest for societies and nations. Vaccination makes good economic sense, and meets the need to care for the weakest members of societies. A comprehensive vaccination programme is a cornerstone of good public health and will reduce inequities and poverty.