is a biological preparation that develops acquired immunity to a
particular infectious disease.
How do vaccines work?
• usually contains an agent that resembles a disease-causing
microorganism
• made from weakened or killed forms of microbe, its toxins, or its
surface proteins
• The agent induces body’s immune system to recognize the agent as a
threat and destroy it.
• immune system keeps a few “memory cells” that memorizes to destroy
any microorganisms associated with that agent
• If the body encounters same virus or bacteria again, it will produce
antibodies to attack the germ
Types of vaccines:
Live attenuated vaccines
• use a weakened (or attenuated) form of the germ that causes a
disease.
• are so similar to the natural infection
• create a strong and long-lasting immune response.
• used against: Measles, Mumps, Rubella, Rotavirus, Smallpox
Inactivated vaccines:
• use the killed version of the germ that causes a disease.
• are created by inactivating a pathogen, typically using heat or
chemicals such as formaldehyde or formalin.
• destroys the pathogen’s ability to replicate, but keeps it “intact” so
that immune system can still recognize it.
• don’t provide immunity as strong as live vaccines
• Used to protect: Hepatitis A, Flu (shot only), Polio (shot only),
Rabies.
Messenger (m) RNA Vaccines:
• RNA code of the SARS CoV-2 virus is inserted into the host cell
• make proteins in order to trigger an immune response.
• do not contain a live virus, no risk of causing disease in the person
getting vaccinated
• shorter manufacturing times
• based on the Moderna model,
• used to protect against: Covid-19.
mRNA Vaccines Different From Traditional Vaccines?
• work by using mRNA is the molecule that essentially puts DNA
instructions into action
• tricks the body into producing some of the viral proteins itself
• Traditional vaccines made up of small or inactivated doses of whole
disease-causing organism
How COVID-19 mRNA Vaccines Work
• are given in the upper arm muscle
• Once (mRNA) are inside immune cells, cells use them to
make protein piece.
• After protein piece is made, cell breaks down the instructions and gets
rid of them.
• cell displays the protein piece on its surface-begin building an immune
response and making antibodies
Advantages of Using mRNA Based Vaccines?
• is non-infectious, non-integrating in nature, and degraded by standard
cellular mechanisms.
• inherent capability of being translatable into protein structure inside the
cell cytoplasm
• are fully synthetic and do not require a host for growth, e.g., eggs or
bacteria.
• can be quickly manufactured inexpensively
• ensure "availability" and "accessibility" for mass vaccination
• Subunit, Recombinant, Polysaccharide, and Conjugate Vaccines:
• They use specific pieces of the germ - like its protein, sugar, or capsid
(a casing around the germ)
• used to protect against: Hib (Haemophilus influenzae type b) disease,
Hepatitis B, HPV (Human papillomavirus), Pneumococcal disease
• Toxoid Vaccines:
• use a toxin (harmful product) made by the germ that causes a disease
• create immunity to the parts of the germ that cause a disease
instead of the germ itself.
• immune response is targeted to the toxin instead of the whole germ.
• Viral Vector Vaccines:
• work by giving cells genetic instructions to produce antigens.
• use harmless viral vectors like adenovirus to deliver these instructions.
• cellular machinery is hijacked by to produce antigens which then
trigger immune response.
different phases in vaccine development?
• four phases–
• Research-identification of the biological pathogen and finding out its
structure through genetic sequencing.
• Pre-clinical testing:-trial vaccine is tried on animals-
• Clinical Trials- on humans-to determine effectiveness of the vaccine
• Regulatory process-undergo an approval by the government regulatory
authorities, for instance Food and Drug Administration in US.
• Manufacturing-approved vaccine is then manufactured
• followed by distribution-
economic aspect of vaccine development:
• Licensing:
• do not receive licensing until a complete clinical cycle of
trials prove that the vaccine is safe
• is followed by a scientific review by a multinational or national
regulatory organization,
Patenting:
• 2020, India and South Africa proposed a waiver from TRIPS
Agreement for prevention, containment or treatment of Covid-19.
• 2001- WTO -Doha Declaration, -clarified that in a public health
emergency, governments could compel companies to license their
patents to manufacturers
• referred to as “compulsory licensing”,
• Section 92 of 1970 Indian Patents Act-
• central government - power to allow compulsory licenses- to be issued
at any time- in case of a national emergency or circumstances of
extreme urgency.
Need for Invoking Compulsory Licensing?
• Plugging Shortage of Vaccine:population of over 900 million above
18 years - about 1.8 billion doses
• Nudging Voluntary Licensing:forcing several pharmaceutical
companies to offer licences voluntarily.
• Leading By Example: Licensing Covaxin would enable India to live
up to its reputation of being ‘pharmacy of the world
• Favourable Regulatory Environment:
Issues
• Complex Intellectual Property Mechanism:ifferent types of IP rights
apply to different steps
• expertise to manufacture -may be a trade secret, and data from clinical
trials - may be protected by copyright.
• Complex Manufacturing Mechanism:manufacturing process has
different steps, some of which subcontracted to other parties.
• patent waiver alone does not empower manufacturers to start vaccine
production immediately.
Significance of Vaccination:
• Prevent mortality:WHO, vaccination prevents between two-three
million deaths each year,
• Reduce expenditure:prevent hospitalisations
• herd protection-some diseases can be eliminated without 100%
immunisation coverage.
• Prevent antibiotic resistance:By reducing need for antibiotics,
vaccines may hinder development of resistant strains
• Socio-economic development:Poor health has shown to stunt
economic growth
• increase life expectancy
Challenges
• Lack of social awareness-due to illiteracy and religious beliefs.
• Inadequate health infrastructure,
• lack of targeted and robust health delivery mechanisms
• Lack of well equipped and trained health care workers.
• Misconceptions about immunisation mostly among poor
• Logistical and Infrastructural issues in storage of vaccines
• Absence of a monitoring mechanism to ascertain degree of vaccination
• Initiatives
• Universal Immunization Programme (UIP):vaccines against 11
diseases nationally and one disease sub-nationally.
• Mass immunization campaigns:Measles-Rubella (MR) vaccination
drive /vaccinated over 3 crore children in three years
• Mission Indradhanush:ensure that full immunization coverage of
90% is achieved
• Pneumococcal Conjugate Vaccine (PCV)-to prevent rotaviral diarrhea
and pneumococcal pneumonia in children.
• Use of Technology:Electronic Vaccine Intelligence Network (eVIN)
system that digitizes the entire vaccine stock management, their
logistics
Vaccines from India
• Covaxin-formulated by Bharat Biotech
• Covishield-a viral vector established on replication-deficient
Adenovirus
Vaccine Equity?
• vaccines should be allocated across all countries based on
needs and regardless of their economic status.
challenges across distribution of COVID-19 vaccine?
• Priority–determined by need, affordability, vulnerability or some other
criterion
• Guideline– how much of the vaccine produced should go to other
countries and at what cost.
• Adult Vaccination program:Vaccination is currently limited to
children and pregnant women
• Distributive hierarchy–: US and other rich countries doling out third
shots - in Africa just 2.2% of people have received even a single dose.
• affordability-Low-income countries -increase healthcare spending by
30-60% -to cover cost of vaccinating
• Post-Vaccination antibody tests:
• Vaccination Hesitancy:
• Supply Chain issue:vaccines of some companies require a minus 70
degree cold chain
Global initiatives for vaccine equity
• COVAX: international partnership which supports vaccine
development, procurement, and distribution globally.
• Global Dashboard for Vaccine Equity: combines latest data on global
roll-out of COVID-19 vaccines
COVID-19 Technology Access Pool (C-TAP): launched by WHO to
facilitate timely, equitable and affordable access of COVID-19 health
products
WHO’s Strategy to Achieve Global Covid-19 Vaccination by mid-
2022:three-step approach, with all older adults, health workers, and
high-risk groups of all ages, vaccinated first,
