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Polio Vaccination Programme in India - Master Guide

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1. Historical Timeline of India's Immunization Milestones

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2. The Vaccines: OPV vs. IPV

Oral Polio Vaccine (OPV) - Sabin Vaccine

• Described by: Sabin, 1957
• Composition: Live attenuated poliovirus - currently bivalent (bOPV) containing types 1 and 3 (type 2 dropped in April 2016 switch)
• Dose: 2 drops orally
• Administration: Tilt child's head back, gently squeeze cheeks or pinch nose to open mouth, let drops fall onto tongue; repeat if child spits out the vaccine
• Storage:
  • Stabilized (MgCl2-stabilized): 4°C for 1 year; 25°C for 1 month
  • Non-stabilized: -20°C (deep freeze); transported on dry ice

1. Live vaccine infects intestinal epithelial cells
2. Virus transported to Peyer's patches - secondary multiplication and viraemia
3. Produces circulating antibodies (IgG) - prevents paralytic polio
4. Stimulates intestinal IgA secretory antibodies - prevents re-infection of alimentary tract and limits transmission
5. Vaccine progeny excreted in faeces - secondary spread immunizes household contacts ("passive immunization")
6. Herd immunity achieved when ~66% of community is immunized

• Easy oral administration - no trained injection personnel needed
• Induces both humoral AND intestinal (mucosal) immunity
• Rapid antibody production; even single dose gives substantial immunity
• Contact spread extends community protection
• Effective in epidemic control
• Inexpensive

• Vaccine-Associated Paralytic Polio (VAPP): Rare but serious - type 3 virus mutates during replication; paralysis can occur in (a) the vaccine recipient and (b) unimmunized contacts

• Immunocompromised individuals (leukaemia, malignancy, corticosteroids) - use IPV instead
• HIV-infected children - use IPV
• Diarrhoea is NOT a contraindication, but the dose must not be counted and should be repeated

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Inactivated Polio Vaccine (IPV) - Salk Vaccine

• Composition: Killed (inactivated) poliovirus, all 3 serotypes
• Administration: IM injection or fractional intradermal injection (0.1 ml fIPV)
• Storage: Refrigerate; do NOT freeze (freezing diminishes potency)

• Induces humoral antibodies (IgM, IgG, IgA serum) - protects the individual from paralysis
• Does NOT induce intestinal/local immunity
• Wild virus can still multiply in the gut and spread to others - major drawback for community protection

• Safe for immunocompromised patients
• Safe for patients on corticosteroids or radiation therapy
• Safe in pregnancy (when immediate protection is needed)
• No risk of VAPP

• Does not prevent gut reinfection or virus shedding
• Requires multiple doses for immunity - unsuitable for outbreak response
• Injections during epidemic times may precipitate paralysis

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3. Why IPV Was Introduced in India (2015) - The Endgame Strategy

1. The last WPV type-2 case globally was in Aligarh, India, 1999
2. 97% of global VDPV (Vaccine-Derived PolyoVirus) cases and 40% of VAPP cases are caused by type-2 virus
3. This necessitated discontinuing type-2 component from OPV (tOPV → bOPV switch)
4. The switch created a "protection gap" - the recent birth cohort was at risk of VDPV-2 and potential WPV-2 lab leakage
5. IPV was introduced on 30 November 2015 as a "safety net" before the tOPV-bOPV switch
6. Given as fractional IPV (fIPV) of 0.1 ml by intradermal injection at 6 weeks and 14 weeks of life

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4. National Immunization Schedule (NIS) - India 2020 (Polio-relevant)

• OPV zero-dose must be given before hospital discharge (in maternity ward) - not at regular immunization sessions to avoid nosocomial infection
• BCG can be given simultaneously with the first dose of OPV
• OPV is given concurrently with DPT or Pentavalent vaccine
• Completing vaccination before 6 months of age is critical (most polio cases occur between 6 months and 3 years)
• OPV can still be given up to 5 years of age as a catch-up dose
• India uses 3 doses + 1 booster OPV schedule (WHO EPI standard)

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5. The Pulse Polio Programme

Background and Launch

• Launched in 1995 following the 1988 WHO Global Polio Eradication Initiative
• Ran alongside (not replacing) routine UIP immunization
• Goal: 100% coverage of all children under 5 years

Structure

• Held in December and January every year on fixed days (Pulse Polio Sundays)
• All children under 5 given additional OPV drops regardless of prior vaccination status
• Coverage: ~172 million children per NID round

• Conducted in high-risk areas only
• Cover ~40-80 million children per round

• Large-scale multi-district operations after NIDs
• Target missed/unreached children in hard-to-reach areas
• House-to-house vaccination of missed children introduced from 1999-2000

Strategy Pillars

1. Fixed-day booth vaccination - vaccination posts at public sites (schools, community centres, railway stations, hospitals)
2. House-to-house campaign - for remote, nomadic, and missed children
3. Transit team vaccination - at railway stations, bus stands, borders
4. Extensive social mobilization - TV/radio spots, cinema ads, national telecoms ringtone replaced with vaccination awareness message, posters, rallies, parades, one-to-one volunteer communication

Challenges Faced

• Remote and hard-to-access communities
• Caste discrimination by some health workers eroded trust
• Vaccine refusal in some areas due to rumours about infertility
• In tropical/developing conditions, children needed 8-10 doses of OPV for full protection (vs. 3 doses in developed countries) - due to interference from other enteric viruses in the gut
• Time demands on health workers reduced capacity for other services

Results

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6. VAPP (Vaccine-Associated Paralytic Poliomyelitis)

• Caused by mutation of OPV virus (especially type 3) during replication
• Affects: (a) vaccine recipients; (b) unimmunized contacts
• Rate: approximately 1 per 2.5-3 million doses distributed
• Risk factors: First dose of OPV carries higher risk; immunocompromised individuals are at greater risk
• VDPV (Vaccine-Derived Poliovirus): Genetically drifted OPV strains that behave like wild virus - 97% caused by type-2
• India had 4 VDPV-2 cases in 2013 (including a 9-month-old boy from Navi Mumbai, July 2013)
• This risk is a key reason IPV was added and tOPV was replaced with bOPV

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7. Coverage Achievements (UIP Data)

• OPV 3-dose coverage: 89%
• BCG: 92%; DPT3: 89%; HepB3: 89%

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8. India's Polio-Free Declaration

• Last WPV cases: January 13, 2011 - West Bengal and Gujarat
• February 25, 2012: India removed from WHO's list of polio-endemic countries
• March 27, 2014: WHO officially certified India and the entire South-East Asia Region as polio-free
• This was considered one of the greatest public health achievements in Indian history

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9. Key Operational Components (UIP Strengthening)

• Alternate vaccine delivery from PHC to sub-centres and outreach sessions
• Retired manpower deployed in urban slums and underserved areas
• Mobility support to District Immunization Officers
• Training of ANMs, cold chain handlers, mid-level managers, refrigerator mechanics
• ASHA mobilization for bringing children to immunization session sites
• Auto-disable (AD) syringes (introduced 2005)
• Open Vial Policy (introduced 2011)
• Cold chain system strengthening and vaccine supply vans

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10. Summary: OPV vs. IPV Side-by-Side

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