Vaccine - Types, Working, Significance and Challenges

Vaccines stand as one of the paramount medical breakthroughs in our history. They function by presenting the body with a harmless version or fragment of a pathogen, activating the immune system. This equips the body to identify and fight the real pathogen later on. Vaccines have been instrumental in curbing, diminishing, or even wiping out diseases like smallpox, polio, and measles. Their extensive application has saved countless lives and substantially lessened the impact of infectious diseases. Ongoing scientific endeavours strive to address continually changing and newly emerging diseases.

Historical Background of Vaccination

For ages, people have sought methods to shield one another from lethal illnesses. Since the 15th century, communities globally have tried to fend off diseases by deliberately introducing healthy individuals to smallpox, a technique termed variolation.

Development of Vaccine

Significant events in the development of vaccines:

• 1796 - Smallpox: Edward Jenner used cowpox material to create immunity to smallpox, marking the birth of the first true vaccine.
  • The term ‘vaccine’ was later coined, taken from the Latin word for cow, Vacca.
• 1885 - Rabies: Louis Pasteur develops the first rabies vaccine after successfully vaccinating a boy bitten by a dog.
• 1890 - Diphtheria: Emil von Behring and Shibasaburo Kitasato produce an antitoxin serum, laying the groundwork for the diphtheria vaccine.
• 1921 - Tuberculosis (BCG): Albert Calmette and Camille Guérin developed the BCG vaccine against tuberculosis.
• 1952 - Polio: Jonas Salk introduced the inactivated polio vaccine (IPV); Albert Sabin later developed the oral polio vaccine (OPV).
• Various efforts taken by WHO for vaccination include
• Intensified Smallpox Eradication Programme (1967): An initiative aimed at eradicating smallpox in over 30 countries through surveillance and vaccination.
• Essential Programme on Immunization (1974): Established to develop and boost immunisation programs globally.
  • Initially targeted diseases like diphtheria, measles, polio, tetanus, tuberculosis, and whooping cough.
• Smallpox Eradication Declaration (1980): WHO declared the world free from smallpox after coordinated vaccination efforts.
• Global Polio Eradication Initiative (1988): Aims to eradicate polio worldwide.
  • Achieved eradication in several regions, with ongoing efforts in remaining endemic areas.
• GAVI (2000): The Global Alliance for Vaccines and Immunisation (GAVI) is a coalition of various stakeholders (WHO, UNICEF, the World Bank, civil society organisations, vaccine manufacturers, and private sector like the Bill & Melinda Gates Foundation); It was created in 2000 to improve access to new and underused vaccines for children living in the world's poorest countries.

Working of Vaccine

• Antigen introduction: Vaccines administer a safe part (antigen) of the infectious agent (like a segment of a virus or bacteria) to the body.
• Activation of immunity: Upon detecting this unfamiliar antigen, the body triggers an immune reaction.
• Antibody generation: To counteract the introduced antigen, the immune system forms specific proteins known as antibodies.
• Creation of memory cells: Certain cells in the immune system, termed memory cells, are developed to retain information about the pathogen.
• Sustained defence: These memory cells persist in the body, offering prolonged defence against that particular pathogen.
• Future encounters: When the individual comes into contact with the actual pathogen later on, the immune system is primed to swiftly generate antibodies to fend it off.
• Enhanced immune reaction: Memory cells ensure that the body's immune reaction is quicker and more potent upon later exposure.

Types of Vaccines

Vaccines are classified based on composition and administration methods, they are essential for disease prevention.

Based on Compositions

Based on composition vaccines are classified as:

Based on Administration

Based on administration vaccines are classified as:

Significance of Vaccine

Vaccines prevent diseases, save lives, reduce healthcare costs, protect vulnerable populations, and bolster global public health through herd immunity and disease eradication. Several advantages of vaccines are:

• Combatting infectious diseases: Vaccines stand as powerful instruments in the fight against infectious ailments.
  • Since the 1960s, measles vaccinations have resulted in a 99% drop in measles occurrences in the U.S.
• Eliminating diseases globally: Comprehensive vaccination campaigns can lead to the total eradication of specific illnesses worldwide. Example: declaration of smallpox's eradication in 1980.
• Mitigating disease impact: Beyond disease prevention, vaccines also diminish the intensity and associated complications for those who may still contract them.
  • The influenza vaccine curtails the disease's harshness, decreasing hospitalisation and mortality risks.
• Financial advantages: Disease prevention through vaccines lessens medical expenses and cuts down on economic impacts.
  • Child vaccinations in the U.S. avert roughly $13.5 billion in direct costs.
• Shielding the At-risk groups: Herd immunity achieved through vaccination safeguards those unable to receive vaccines, like those with specific allergies or weakened immune defences.
  • Vaccinating most individuals against pertussis (whooping cough) ensures protection for newborns not yet fully vaccinated.
• Staving off disease return: Persistent immunisation practices are essential to ward off the return of diseases that have become uncommon.
  • Global vaccination efforts have slashed polio cases by over 99% since 1988, but neglecting immunisation might cause a rapid comeback.
• Curbing antibiotic resistance: By warding off bacterial diseases, vaccines decrease antibiotic use, helping in the battle against antibiotic resistance.
  • Pneumococcal conjugate vaccine has cut down occurrences of antibiotic-resistant invasive pneumococcal infections.
• Defence against adapting diseases: Vaccine development adapts in the face of evolving pathogens.
  • The flu vaccine is recalibrated yearly to match dominant strains, and the rapid creation of COVID-19 vaccines is a testament to this adaptability.
• Endorsement of lifelong health: Certain vaccines offer enduring defence against illnesses that could lead to lasting ailments or cancers.
• The HPV vaccine wards off the virus types causing numerous cervical cancers.
• Augmenting public health standards: Mass immunisation uplifts the collective health of communities and lightens the load on medical infrastructures.
  • After the launch of the rotavirus vaccine, there was a marked drop in severe diarrhoea-related hospital stays in young children.

Challenges associated with Vaccines

Vaccines are pivotal in combating infectious diseases, yet their creation, dissemination, and public reception entail a range of complex challenges. Several challenges associated with vaccines are:

• Production and Logistic Challenges
  • Research & Innovation: Identifying safe and potent formulations demands significant time, research, and monetary resources.
  • Example: The development of an HIV vaccine
  • Efficacy & Safety evaluation: Multi-phase clinical tests are pivotal for verifying safety and performance, though they can be protracted and costly.
  • Example: Pause of AstraZeneca Covid Vaccines.
  • Production expansion: Shifting from laboratory settings to large-scale manufacturing while maintaining quality presents challenges.
  • Example: Early stages of Covid-19 vaccines.
  • Cost: High costs can limit vaccine availability.
    • Example: Pneumococcal vaccines are expensive, impacting distribution in low-income countries.
  • Supply chain: Ensuring stable raw material supply is crucial.
    • Example: Global shortage of eggs during H1N1 influenza
  • Cold chain management: Some vaccines need specific temperature control.
    • Example: The Pfizer-BioNTech COVID-19 vaccine
  • Biosafety: Handling pathogens demands safety precautions.
  • Accessibility Challenges
  • Distribution infrastructure: Inadequate infrastructure can hinder vaccine delivery.
    • Example: Remote areas in countries like Chad or Afghanistan.
  • Intellectual Property and licensing: Patent issues can restrict the production of cheaper generic versions.
  • Example: HIV/AIDS medication accessibility faced challenges until patent flexibilities allowed generic production.
  • Inequitable global distribution: Wealthier countries may secure larger vaccine stocks, leaving fewer doses for low-income countries.
    • Example: Covid-19 Vaccine distribution.
• Vaccine Hesitancy
  • Misinformation and myths: Misleading information can lead to unfounded fears about vaccines.
  • Example: Myth about the relation between Autism and MMR vaccine.
  • Cultural and religious beliefs: Some communities refuse vaccines based on cultural or religious principles .
    • Example: Opposition to Polio vaccines in Pakistan
  • Lack of knowledge: Insufficient awareness about vaccine benefits and the diseases they prevent can hinder acceptance.
• Responsiveness Challenges
  • Age: The immune response can vary with age. Example: The influenza vaccine where the elderly, despite being vaccinated, might still be at risk due to a diminished immune response.
  • Nutritional status: Malnutrition can weaken the immune system and reduce vaccine efficacy.
  • Genetics: Genetic makeup can influence how one responds to a vaccine. Some genetic profiles might result in stronger immune responses than others.
• Other Challenges
  • Vaccine-induced infection: It refers to the rare occurrence where a vaccine causes the very disease it's designed to prevent.
  • This situation is primarily a concern with live attenuated vaccines.
  • Example: Oral Polio Vaccine (OPV) caused vaccine-associated paralytic poliomyelitis (VAPP) in a small number of recipients.
  • Comorbidities challenges: Developing vaccines for people with comorbidities is a challenging task.
  • Booster shots: Some vaccines require multiple doses for full protection. 
    • Example: The HPV vaccine initially required three doses over six months.
  • Duration of protection: Some vaccines don't offer lifelong immunity and need boosters.
    • Example: Tetanus shots are recommended every 10 years

Video:

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• How mRNA vaccines work

Vaccines UPSC PYQs

Question 1: Consider the following: (UPSC Prelims 2021)

1. Bacteria
2. Fungi
3. Virus

Which of the above can be cultured in an artificial/synthetic medium?

(a) 1 and 2 only

(b) 2 and 3 only

(c) 1 and 3 only

(d) 1, 2 and 3

Answer: (a)

Question 2: With reference to recent developments regarding ‘Recombinant vector Vaccines’, consider the following statements: (UPSC Prelims 2021)

1. Genetic engineering is applied in the development of these vaccines.
2. Bacteria and viruses are used as vectors.

Which of the statements given above is/are correct?

1. 1 only 
2. 2 only
3. Both 1 and 2
4. Neither 1 nor 2

Answer: (c)

Question 3: The Human Papilloma Virus vaccine has been making the headlines in recent months. Who make the ideal candidates for receiving this vaccine and what are its benefits? (UPSC Mains 2012)

Vaccines FAQs

Q1. What is Herd Immunity?

Ans. Herd immunity occurs when a large portion of a community becomes immune to a disease, reducing its spread and protecting those not immune, often through vaccination or previous infection.

Q2. What is Vaccine hesitancy?

Ans. Vaccine hesitancy refers to the reluctance or refusal to vaccinate despite available vaccination services, often due to fears, misconceptions, or lack of confidence in vaccines.

Q3. What is immunisation?

Ans. Immunisation is the process by which a person becomes protected against a disease through vaccination. It involves introducing a vaccine into the body to stimulate the immune system to recognize and fight specific viruses or bacteria, preventing the disease in the future.

Q4. What are the major diseases eliminated due to vaccination?

Ans. Smallpox was eradicated globally by 1980 through vaccination. Polio has been eliminated from most countries, with a 99% reduction since 1988. Rinderpest in cattle was eradicated in 2011 via vaccination.

Q5. Who developed the first vaccine?

Ans. Edward Jenner developed the first vaccine in 1796, using cowpox material to create immunity to smallpox, marking the beginning of modern vaccinology.