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VACCINES/IMMUNIZATIONS/ CHALLENGES/PRACTICES/COVERAGE/EVALUATION

VACCINES/IMMUNIZATIONS/ CHALLENGES/PRACTICES/COVERAGE/EVALUATION. Learning objectives. Explain the concepts of vaccination Evaluate the immunization status of a child and recommend appropriate vaccinations Discuss the monitoring, barriers and challenges to immunization programmes

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VACCINES/IMMUNIZATIONS/ CHALLENGES/PRACTICES/COVERAGE/EVALUATION

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  1. VACCINES/IMMUNIZATIONS/CHALLENGES/PRACTICES/COVERAGE/EVALUATION

  2. Learning objectives • Explain the concepts of vaccination • Evaluate the immunization status of a child and recommend appropriate vaccinations • Discuss the monitoring, barriers and challenges to immunization programmes • Understand need for new vaccines and the approaches to vaccine design • List some vaccine candidates

  3. OUTLINE • Introduction • Basic immunology • Vaccine recommendattion • Contraindications • Monitoring immunization • Barriers to immunization • Challenges • Prospects/new vaccines

  4. INTRODUCTION • IMMUNITY - “Self vs Non self -protection from microbes recognised as foreign • Primary immune response: following antigenic challenge antibodies, specific helper and effector T lymphocytes including those producing cytokines and killer T cells are produced • Immunological memory

  5. Historical perspectives • Smallpox- most feared-20-30% case fatality rates- leaving survivors scarred for life • Variolation practiced as early as 10th century AD • Edward Jenner – 1st to publish in 1796 • Rabies vaccine by Louis Pasteur 100 years later

  6. DEFINITIONS • Immunization is the process of inducing immunity artificially • Vaccination is the administration of a vaccine for the prevention of disease

  7. Definitions contd • Active immunization is that which induces in the recipient a degree of immunity similar to that achieved from the natural infection and is able to prevent clinical disease. • Involves stimulating the immune system to produce antibodies or cell mediated immunity against an infectious agent • Produced by the individual’s immune system • Immunity is usually long lasting

  8. Definitions contd • Passive immunization is the administration of exogenously preformed antibodies • Immunity is temporary • Commonest is transplacental

  9. Immunizing Agents • VACCINE :any preparation which when administered is able to stimulate the immune system to produce specific responses that inactivate, destroys or suppresses a given pathogen • Live attenuated • Inactivated

  10. Live Attenuated vaccines • Produced by modifying a naturally occuring organism (wild) usually by repeated culturing • Retains the ability to replicate and produce immune response similar to natural infection • Circulating antibody may interfere with response

  11. Live attenuated vaccines • Long lasting immunity • One dose usually suffices • Examples of live attenuated viruses- poliomyelitis, measles, rubella , mumps, rabies, varicella, yellow fever, rotavirus, influenza • Examples of live attenuated bacteria- Bacille calmette guerin, typhoid

  12. Inactivated vaccines • The organism is inactivated with heat and or chemicals (formalin). With fractional vaccines it is further treated to purify only those components to be included in the vaccine • Non replication so cannot cause disease • Less interference from circulating antibodies • Requires more doses 3-5 • Mostly humoral immune response • Antibody titres diminish with time

  13. Examples of inactivated vaccines • Whole organism -Viral- poliomyelitis (salk) hepatitis A, Rabies,influenza -Bacteria- pertussis, typhoid, cholera, plague, anthrax • Fractional - subunit – hepatitis B, acellular pertussis, human papilloma virus - toxoids – diphtheria, tetanus

  14. Inactivated vaccines contd • Polysaccharide – pneumococcal,meningococcal,salmonella typhi • Conjugate polysaccharide- Hib, pneumococccal, meningococcal • Recombinant – hepatitis b , human papilloma virus, influenza ,

  15. Other components of vaccines • Suspending fluids- sterile water, saline or other complex fluid containing small amounts of proteins • Preservatives, stabilizers, antimicrobial agents-gelatin, 2-phenoxyethanol, specific antimicrobial agents. THIMEROSAL-contains ethyl mercury • Adjuvants-enhances immune response- aluminium salts, ASO4

  16. Immune globulins • Immune globulin – homologous pooled antibody. From many adults. Contains antibodies to many antigens. hepatitis A, measles • Homologous human hyperimmune globulin. From humans with high levels of specific antibodies. PEP hepatitis B , rabies , tetanus, varicella • Heterologous hyperimmune serum(antitoxin) . From animals. botulism, diphtheria • Monoclonal antibodies derived from clone of antibody producing cells RSV.-Palivizumab

  17. Determinants of immune response • Chemical and physical state of the vaccine • Route/site of administration • Vaccine dose • Immunogenicity of the vaccine • HOST FACTORS- age -sex -nutrition -Preexisting antibodies -genetics -immune status -pregnancy

  18. Classes of protective antibody • Antitoxins- inactivates soluble toxic protein products • Opsonin- facilitates phagocytosis • Lysins- interracts with components of serum complement • Neutralising antibodies- prevents proliferation of infectious virus • Antiadhesins- prevents adhesion to mucosal surfaces

  19. Vaccine recommendation Factors to consider • Epidemiology-incidence, age, sex • Age specific morbidity and mortality • Risk of adverse events • Cost effectiveness • Age of recommended health care visits • Efficacy of the vaccine

  20. Vaccine recommendation cont’d Vaccinations are generally recommended at the age of • Significant risk of disease and complications • Protective immunologic response • Also recommended for special situations eg SCA, HIV

  21. Recommendations in Nigeria • Birth – OPV 0, BCG, HBV1 • 6weeks –OPV1, PENTA1(HBV,DPT,HIB),PCV1,ROTA1 • 10weeks – OPV2, PENTA2,PCV2,ROTA2 • 14weeks – OPV3, PENTA3,PCV3,IPV • 9months – Measles, YF

  22. Recommendations in Nigeria contd • TT 1 at 1st contact no protection • TT2 4wks later 80% protection for 3years • TT3 6mths later 95% protection for 5 years • TT4 1year later or in subsequent pregnancy 99% protection for 10 years • TT5 1 year later or in subsequent pregnancy 99% protection for ?life

  23. Objectives of immunization programme • Not just individual protection • Decrease morbidity and mortality from target diseases • Increase herd immunity – resistance of a group to invasion and spread of an infectious agent due to immunity of a large proportion of the group High coverage needed to achieve this

  24. Vaccine delivery • Routine immunization • Response to an epidemic • Supplemental immunization activities • Mop up immunization • Mobile or fixed locations

  25. Practical points • Short intervals • Delayed or lapsed immunization • Uncertainty • Simultaneous vaccines • Immunization records- type of vaccine - lot number, batch number, - manufacturer - date and location

  26. Immunization in special circumstances Some vaccines are recommended for • Those at increased risk of complications from the disease • Those at increased risk of exposure to the disease

  27. Immunization in special circumstances • Pneumococcal polysaccharide vaccine –SCA, anatomic asplenia, nephrotic syndrome, renal failure, HIV, organ transplant • HIV- all vaccines if asymptomatic -BCG and yellow fever contraindicated if symptomatic - IPV preferred to OPV • Cerobrospinal meningitis • Rabies • Live vaccines generally not given to immunocompromised children

  28. Contraindications • Anaphylaxis • Encephalopathy • Progressive neurologic disorders • Immunodeficiency disorder, immunosuppressive therapy • Pregnancy • Any illness requiring admission to hospital defer immunization

  29. Precautions • Fever> 40.5OC • Collapse /shock • Unconsolable crying • Guillan barre syndrome For MMR Blood transfusion thrombocytopenia

  30. NOT CONTRAINDICATIONS • URTI • Mild fever • Diarrhoea – repeat dose • Cerebral palsy • Breast feeding • Antimicrobial therapy

  31. Adverse reactions • Pain, swelling, redness, soreness • Fever • Anaphylaxis • Encephalopathy- convulsions, coma • Rash/urticaria

  32. Cost Effectiveness • Savings on treatment cost • ↓mortality • ↓morbidity and disability • Avoidance of intangible costs(suffering) • External /spillover benefits Small pox eradication saving 32billion dollars Poliomyelitis eradication- 3 countries still endemic Hib immunization-Reduced invasive HiB disease by 99%

  33. Monitoring • Immunization coverage • Vaccine safety-vaccine adverse event reporting system -epidemiological studies of incidence of adverse events Eg intussuception following rotavirus investigation of MMR and autism Thimerosal containing vaccines and neurodevelopmental disorders

  34. Immunization coverage • Percentage of target population that have received immunization • Often evaluated in children aged 12-23months – estimates recent immunization performance • May be evaluated in the target population for a given vaccine eg under fives following NIDs • Is an indicator of access to and utilisation of immunization services

  35. Uses of immunization coverage • Monitor performance of immunization services locally, nationally and internationally • To guide strategies for eradication, elimination and control of vaccine preventable diseases • Identify areas of immunization systems that require additional focus/resources

  36. Sources of immunization coverage data • Routine data • Immunization coverage surveys- cluster survey - Lot quality assurance - 75 house survey

  37. Indicators for monitoring immunization • Timeliness • Drop-out rate–measures effectiveness of tracking activities, quality of immunization programme • Missed opportunities-compare DPT&OPV, measles &YF • Vaccine wastage

  38. Indicators for monitoring immunization • Monitoring of adverse events • Disease surveillance/outbreak investigation • Age specific susceptibility • Cost of immunization • Reasons for undervaccination

  39. Current coverage in Nigeria 2011 2013(males) 2013(females) 2013(DHS) • BCG- 54.6% 52.9 49.3 51.2 • DPT1- 51.6% 52.4 49.3 50.6 • DPT3-34.9% 39.4 37.0 38.2 • HepB1- 25.9% • HepB3-27.6% • Measles- 43% 43.1 41.0 42.1 • All vaccines-23.8% 25.7 25.0 25.3 • No vaccines 20.0 21.4 20.7

  40. BARRIERS TO IMMUNIZATION • Consumer factors personal- ignorance, wrong info, lack of motivation sociocultural- education, place of delivery, religion, maternal age Community factors- traditional rulers, religious leaders

  41. BARRIERS TO IMMUNIZATION • Systems –impeding practice policies - vaccine costs - lack of tracking -Long waiting - poor funding - Donor activities -lack of political will -political interference - low staff morale -poor monitoring

  42. BARRIERS TO IMMUNIZATION • Provider attitudes that lead to missed opportunities. Amissed opportunity Occurs when an individual in whom there is no contraindication does not receive the vaccine(s) for which he/she is eligible when he/she visits a health facility. Can occur during curative /preventive

  43. Missed opportunity • causes of missed opportunities • non availability of vaccine • Not checking immune status • Failure to give simultaneous injections • Failure to provide info to parents • Failure to immunize everyday • Failure to open multiple dose vials for few clients

  44. challenges • Vaccine production • Funding- • Providing the vaccines- programme -logistics - vaccine delivery -vaccine storage - tracking - health care personnel

  45. Challenges contd • Demand for the vaccine- communication -social stability • Injection safety • Adverse events • Surveillance and monitoring • Sufficient market • Increasing complexity of schedules • Evolving organisms • Globalisation of disease • TERRORISM, POLITICISATION,

  46. ARE THERE CHALLENGES PECULIAR TO NIGERIA?

  47. Some challenges peculiar to Nigeria • Frequent strikes by health care workers • Insurgency • Lack of budget /release for specific immunization activities • Non production of routine immunization data tools by most states once seed stock is exhausted • Lack of timely use of monthly Routine immunization data for action

  48. FOOD FOR THOUGHT • A SPATE OF COMMUNAL CLASHES HAVE OCCURRED IN YOUR LOCAL GOVERNMENT -List the effects on immunization activities -what steps can be taken to avoid outbreaks of vaccine preventable diseases? • AS A PROGRAMMEOFFICER YOU NOTICE THAT ROUTINE DATA SHOWS IMMUNIZATION COVERAGE IS DROPPING -List the steps you would take to address this challenge

  49. Polio eradication and endgame • Global polio eradication initiative launched in 1988 • Reduced polio cases by 99% • Reduced number of endemic countries from 125 to 3 • Type 2 polio eradicated since 1999 • Type 3 last isolated in november 2012 • Vaccine associated paralysis due to type 2 • 97% of circulatiing vaccine derived polio virus are type 2

  50. Polio eradication objectives • Polio eradication and the endgame • Stop all WPV transmission by 2014 and end new cVDPV outbreaks within 120 days of 1st confirmed case • Hasten interruption of WPV transmission and decrease risk of importation of WPV and cVDPV and strengthen RI • Certify all regions polio free and safely contain all polio virus stocks • Ensure polio free world is permanent

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