PE18.1-14 | Immunization — Glossary

A safety framework for vaccine administration: right patient, right vaccine, right dose, right route, and right time; adapted from the medication-administration '5 rights'.

Adverse Event Following Immunization — any medical occurrence temporally associated with vaccine administration; cold chain failure-related vaccine inefficacy may present as an apparent AEFI (vaccine-preventable disease in a vaccinated child) or as a cold chain failure event requiring separate reporting.

Any untoward medical occurrence that follows immunisation and does not necessarily have a causal relationship with the vaccine; classified by WHO-CIOMS as vaccine-product-related, quality-defect-related, immunisation error-related, anxiety-related, or coincidental.

All adverse events following immunization must be reported to the block/district immunization surveillance officer using the standard Government of India AEFI reporting form; serious AEFI (anaphylaxis, hospitalisation, death) require urgent reporting.

Surveillance of all children under 15 years with sudden-onset flaccid paralysis to detect poliovirus; the global standard indicator is ≥2 AFP cases per 100,000 children under 15 years per year (non-polio AFP rate).

A severe, systemic, immediate hypersensitivity reaction that can follow vaccination; onset typically within 15–30 minutes; managed with adrenaline 0.01 mL/kg of 1:1000 solution IM into the anterolateral thigh.

Immediate treatment: adrenaline (epinephrine) 1:1000 solution 0.01 mg/kg IM (max 0.5 mg) into the anterolateral thigh; repeat every 5–15 min if needed. All immunization sites must stock adrenaline.

Rare severe allergic reaction occurring typically within 15 minutes of vaccination; signs: breathing difficulty, severe urticaria/angioedema, pallor, limpness, collapse; treatment: adrenaline 1:1000 0.01 mg/kg IM (max 0.5 mg) into anterolateral thigh.

Trained female health worker providing primary healthcare services including immunisation at sub-centre and outreach levels; the primary vaccinator in India's rural immunisation delivery system.

The preferred intramuscular injection site for infants under 1 year, located on the lateral aspect of the middle third of the thigh, avoiding major nerves and vessels.

Trained community health worker in every Indian village who serves as a bridge between the formal health system and the community; plays a key demand-generation role in immunisation by tracking due lists and mobilising families.

A communication technique to verify comprehension: after counselling, ask the parent to repeat in their own words what they understood — e.g., 'Can you tell me what reactions to watch for at home?' — to confirm understanding before they leave.

A syringe designed to become non-functional after a single use by locking the plunger; mandated by the UIP to prevent needle reuse and reduce programme-error AEFI.

The average number of secondary infections generated by one infectious case in a fully susceptible population with no prior immunity and no control measures; determines the herd immunity threshold.

Used vaccine vials and syringes must be disposed of as biomedical waste per CPCB guidelines: vials in yellow bags (pharmaceutical waste); syringes in puncture-proof sharps containers.

Indian statutory framework (Ministry of Environment, Forest and Climate Change) governing the segregation, storage, transport, and disposal of biomedical waste, including immunization-session sharps and vials.

The practice of administering missed vaccines to older children, continuing the series from the last dose received rather than restarting; respects minimum intervals between doses.

The proportion of CD4+ T-lymphocytes among total lymphocytes; used to assess immune status in HIV-infected children; <15% indicates severe immunosuppression in which live vaccines are generally contraindicated.

Age calculated from the date of birth (not from the expected due date); used as the reference for all NIS vaccine scheduling in preterm infants, not corrected gestational age.

The unbroken series of refrigerated storage and transport steps that maintains vaccine temperature and potency from manufacturer to point of administration.

An ice pack that has been allowed to reach 0°C (room temperature until water inside is just melting) before use in a vaccine carrier; prevents the carrier from dropping below 0°C and freezing adsorbed vaccines.

A pattern of birth defects — sensorineural deafness, cataracts, cardiac defects, microcephaly — resulting from transplacental rubella virus infection during the first trimester; prevented by MR vaccination achieving herd immunity in women of childbearing age.

A vaccine in which a polysaccharide antigen is chemically linked to a protein carrier, enabling T-cell-dependent immune responses in infants under 2 years (e.g., PCV, Hib conjugate, TCV).

Chronological age minus the number of weeks of prematurity; used for developmental milestone assessment in preterm infants but NOT for vaccine scheduling.

Cold chain storage at −15°C to −25°C; used for long-term storage of heat-sensitive live vaccines, principally OPV, and freeze-dried vaccines at central/district stores.

HIV PCR testing of HIV-exposed infants, typically at 6 weeks of age, to detect vertical (mother-to-child) HIV transmission; a positive test at 6 weeks confirms infant HIV infection.

Bacteria with a polysaccharide capsule (Streptococcus pneumoniae, Haemophilus influenzae type b, Neisseria meningitidis) that require splenic IgM opsonisation and phagocytic clearance; infections are particularly severe in asplenic patients.

India's digital system for real-time monitoring of vaccine stock and cold-chain status at all UIP vaccination sites, using smartphones and IoT temperature sensors.

Explicit, verbally stated or written consent; required for non-routine vaccines, clinical trials, and procedures with significant risk disclosure requirements.

A condition incorrectly believed to preclude vaccination (e.g., mild fever, prematurity, family history of reactions); withholding vaccines for false contraindications creates missed opportunities and leaves children unprotected.

Vaccine stock rotation practice: vaccines with the earliest expiry dates are placed at the front of ILR shelves and used first, minimising wastage due to expiry.

0.1 mL intradermal dose of inactivated poliovirus vaccine (all 3 serotypes) given at 6 and 14 weeks in the India NIS alongside OPV; introduced to provide serotype-2 protection after withdrawal of trivalent OPV.

One-fifth the standard IPV dose (0.1 mL) given intradermally to elicit comparable poliovirus immunity while conserving vaccine supply; administered at 6 and 14 weeks under the NIS.

Vaccines containing aluminium adjuvant (DPT, pentavalent, TT/Td, HepB, fIPV) that are permanently inactivated by freezing; must never be stored below 0°C.

The proportion of children aged 12–23 months who have received all vaccines scheduled in the NIS for that age; the primary indicator of UIP programme performance in NFHS and HMIS surveys.

Impaired splenic clearance function in the absence of surgical removal, caused by progressive splenic infarction in sickle cell disease; results in similar susceptibility to encapsulated bacteria as surgical asplenia.

A health psychology framework explaining health behaviour in terms of perceived susceptibility, perceived severity, perceived benefits, and perceived barriers — applicable to understanding vaccine hesitancy.

Live-attenuated vaccines (OPV, BCG, MR) whose potency is rapidly lost at temperatures above +8°C; most heat-sensitive is OPV.

Indirect protection of unimmunized individuals when a sufficient proportion of the community is immune, reducing pathogen transmission; the threshold for measles is approximately 92–95%.

The proportion of a population that must be immune to a pathogen to prevent sustained transmission; calculated as 1 − (1/R0). Higher-transmissibility pathogens (high R0) require higher thresholds.

An encapsulated gram-negative bacterium that causes bacterial meningitis, epiglottitis, and septicaemia predominantly in children under 5; prevented by Hib conjugate vaccine (included in pentavalent).

Recombinant virus-like particle (VLP) vaccine protecting against oncogenic HPV types 16/18 (cervical cancer) and types 6/11 (genital warts in quadrivalent/nonavalent); 2 doses for ages 9–14, 3 doses for ≥15 years.

A device that destroys a needle at the point of use by shearing it from the syringe barrel, preventing needle reuse and eliminating the need for recapping; mandatory in India's UIP.

An AEFI characterised by sudden pallor, limpness, and unresponsiveness occurring within 48 hours of pertussis-containing vaccines; generally self-limiting with no long-term sequel but must be reported.

The national professional body for paediatrics in India; its Advisory Committee on Vaccines and Immunization Practices (ACVIP) publishes recommended immunization schedules that include vaccines not yet in UIP.

A refrigerator with a thick ice-lining that maintains 2–8°C for storage of most vaccines; retains temperature during power outages, making it suitable for PHC cold chain.

Consent inferred from a person's behaviour rather than explicitly stated; in routine immunization, a parent who presents a child at a vaccination session and exposes the injection site is understood to be consenting to vaccination.

A vaccine containing killed pathogens or their components that cannot replicate; safe in immunocompromised hosts but requires multiple doses for primary immunity (e.g., IPV, hepatitis A).

A parent's right to decline vaccination for their child after receiving complete, accurate information about the risks and benefits; must be documented in the immunization record with date, information provided, and the parent's decision.

Injection into the dermis, used for BCG vaccine; performed at a 15° angle with a 26 G needle, producing a visible pale bleb of 5–7 mm as a quality indicator.

The principle that transformed substances (such as porcine gelatin fully converted through processing) may be permissible in Islamic law when the original substance is no longer recognisable; used by religious authorities to permit certain vaccine formulations containing trace gelatin.

Concentrated immunoglobulin preparation given IV; the passively transferred antibodies can neutralise live attenuated vaccines, requiring deferral of MR and varicella for up to 10–11 months after high-dose administration.

A vector-borne flaviviral encephalitis transmitted by Culex mosquitoes, endemic in at least 24 Indian states; 20-30% case-fatality, 30-50% neurological sequelae in survivors; JE vaccine included in NIS for endemic districts.

A vaccine containing weakened, viable pathogens that replicate in the host to produce robust, long-lasting immunity; contraindicated in significant immunodeficiency (e.g., BCG, OPV, MR, rotavirus).

The portable immunization record kept by the caregiver; documents all vaccines administered, dates, batch numbers, and next-due dates; legally belongs to the caregiver.

Quadrivalent meningococcal conjugate vaccine protecting against Neisseria meningitidis serogroups A, C, W, and Y; mandatory for Hajj/Umrah pilgrims and recommended for asplenic patients and meningitis-belt travellers.

India's intensified immunisation programme launched in 2014 targeting zero-dose and under-vaccinated children in high-priority districts through systematic catch-up campaigns; multiple rounds conducted nationwide.

The Government of India's schedule specifying vaccines, target age-groups, doses, and routes for all vaccines in the public programme; updated periodically by MoHFW.

India's flagship health mission providing the programmatic and financial framework for rural and urban primary healthcare, including immunisation, maternal health, IMNCI, and nutrition programmes.

The absolute prohibition on replacing a cap onto a used needle after injection; recapping is the leading cause of needle-stick injury in immunization workers.

A procedural discipline ensuring that critical items (needle, syringe tip, rubber septum) are never touched or contaminated during vaccine preparation and administration.

WHO/NIS policy permitting reuse of eligible opened multi-dose vaccine vials across sessions if VVM, expiry, temperature, and sterility criteria are met; does NOT apply to reconstituted lyophilised vaccines.

Unrelated concept note: blood products and IVIG interfere with live vaccine immunogenicity by providing pre-formed antibodies that neutralise attenuated virus — minimum deferral intervals must be observed before MR and varicella after blood products.

A life-threatening, rapidly fatal bacterial sepsis caused by encapsulated organisms (Streptococcus pneumoniae, Haemophilus influenzae b, Neisseria meningitidis) in asplenic patients; preventable by appropriate vaccination and penicillin prophylaxis.

15 mg/kg per dose orally, every 6 hours as needed, maximum 4 doses per 24 hours; for fever and pain after vaccination in children. Do not use aspirin or ibuprofen routinely.

A conjugate vaccine covering major pneumococcal serotypes causing invasive pneumococcal disease; given as a primary series with a booster in infancy under NIS/IAP schedule.

Long-term daily low-dose amoxicillin or phenoxymethylpenicillin given to asplenic children to prevent pneumococcal sepsis; complementary to (not a replacement for) vaccination.

A combination vaccine containing five antigens: diphtheria toxoid, pertussis (whole-cell killed), tetanus toxoid, hepatitis B, and Hib polysaccharide-protein conjugate; given at 6, 10, and 14 weeks in the India NIS.

15–30 minutes during which the vaccinated child remains at the immunization site to allow detection and management of anaphylaxis; mandatory for all vaccines at all sessions.

The period before planned organ transplantation during which catch-up vaccines are administered; live vaccines must be given at least 4 weeks before the expected start of immunosuppression.

An adverse event caused by errors in vaccine preparation, handling, or administration — preventable failures in the immunization workflow, as distinct from intrinsic vaccine properties.

Standardised brief communication given to parents after vaccination covering: expected reactions and timing, home management (paracetamol for fever), red-flag signs requiring return, and next appointment.

India's national pharmacovigilance programme, which includes the AEFI surveillance system through district and state AEFI committees reporting to the national level.

Average number of secondary cases generated by one infectious individual in a fully susceptible population; determines epidemic potential and herd immunity threshold for control or elimination.

The process of adding the manufacturer-supplied diluent to a freeze-dried (lyophilised) vaccine (BCG, MR, varicella) to restore it to liquid form; reconstituted vaccine must be used within 4 hours and then discarded.

A WHO/UNICEF operational strategy for immunisation programmes to identify and systematically re-engage under-served populations through targeted outreach, supply planning, and community mobilisation.

Live-attenuated oral vaccine preventing severe rotavirus gastroenteritis; must not be initiated after 15 weeks of age due to intussusception risk; 2–3 doses in primary series under NIS.

An AEFI that results in hospitalisation, significant disability or incapacity, life-threatening illness, death, or congenital anomaly; requires mandatory reporting to the district AEFI committee within 24 hours.

A quality-check procedure to detect freeze-damaged adsorbed vaccines (DPT, Hep-B, pentavalent, fIPV): the suspect vial and an intact control vial are vigorously shaken; freeze-damaged vaccines form a compact sediment that does not re-suspend, while intact vaccines resuspend uniformly.

Vi polysaccharide conjugated to tetanus toxoid; immunogenic from 6 months; introduced into NIS from 2022 to prevent typhoid fever, which remains endemic in India.

A vaccine made from inactivated bacterial toxin; confers immunity against the toxin-mediated effects of disease rather than infection (e.g., tetanus toxoid, diphtheria toxoid).

India's national programme launched in 1985 under NHM/RCH to achieve universal coverage of all children with scheduled vaccines; targets ~27 million infants and ~30 million pregnant women annually.

India's national immunization programme under the Ministry of Health and Family Welfare, providing free vaccination against 12+ vaccine-preventable diseases to all children from birth.

The small, pale, tense raised wheal (5–7 mm) produced by correct intradermal injection; its presence confirms the needle tip was in the dermis rather than subcutaneous tissue.

A portable insulated container used for transporting vaccines to outreach sessions; maintains correct temperature for up to 12 hours when loaded with conditioned ice packs.

The delay in acceptance or refusal of vaccines despite availability of vaccination services (WHO SAGE 2014); exists on a spectrum and is often addressable through provider communication.

An infectious disease against which a licensed, effective vaccine exists and which is included in national or regional immunisation schedules as a public health priority.

A heat-sensitive label attached to each vaccine vial that changes colour irreversibly upon cumulative heat exposure above a threshold; used to detect heat-damaged vaccines at the point of administration.

A rare paralytic complication of OPV (approximately 1 per 2.7 million doses) occurring in recipients or their contacts; virtually eliminated in NIS with shift to fIPV for type-2 poliovirus.

An adverse event caused by the inherent properties of a correctly administered vaccine; an expected, immunologically mediated response (e.g. fever post-DPT, BCG ulcer).

A rare complication of OPV (~1 in 750,000 for first dose) in which the live-attenuated poliovirus reverts to neurovirulence; one of the reasons IPV/fIPV has been added alongside OPV in the India NIS.

Reference to the 1998 Wakefield et al. Lancet paper claiming MMR causes autism; retracted in 2010 for fraud and ethical violations; the author was struck off the medical register; no subsequent credible evidence has supported the claim.

Framework identifying Complacency (perceived low disease risk), Convenience (access/structural barriers), and Confidence (trust in safety/efficacy) as the three root causes of vaccine hesitancy.

Live-attenuated vaccine providing long-lasting protection against yellow fever virus; available only at designated vaccination centres in India; required certificate for entry into some countries; contraindicated in severe immunocompromise.