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Questions and Answers
What is the primary purpose of passive surveillance in monitoring vaccine-preventable diseases?
Which of the following vaccines is considered mandatory for entry into certain countries?
What is one of the main causes of vaccine hesitancy?
In low and middle-income countries, the main barriers to vaccine access include all of the following EXCEPT:
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Which type of surveillance is defined by identifying illness clusters before diagnoses are confirmed?
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What is an emerging infectious disease?
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Health facilities destroyed by conflict directly impact immunisation coverage in which way?
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Which of the following diseases is NOT under mandatory notification in Australia?
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Vaccine hesitancy can lead to which of the following outcomes?
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What is a key challenge related to vaccine development?
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Which factor is most likely to cause vaccine hesitancy among parents?
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What percentage of children worldwide received an initial DTP dose, according to recent statistics?
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What is the key purpose of conducting a thorough analysis following an outbreak?
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Which disease has seen a particularly significant increase in global cases due to vaccine hesitancy?
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What is the primary distinction between vaccination and immunisation?
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Which of the following is a benefit of immunisation?
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What is a characteristic of monovalent vaccines?
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What factor has the greatest influence on global immunisation coverage improvement in recent years?
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Which type of vaccine is an example of a component vaccine?
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What is 'no jab no pay' legislation designed to achieve?
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What is the main goal of a national immunisation program?
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Which of the following describes herd immunity?
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How is vaccine efficacy generally measured?
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Which of the following is a component of managing outbreaks of vaccine-preventable diseases?
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What is meant by 'vaccine effectiveness'?
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What common barrier to vaccination exists in lower-middle-income countries (LMICs)?
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What characteristic differentiates a polyvalent vaccine from a monovalent vaccine?
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What is a primary health care aspect of immunisation efforts?
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Study Notes
Vaccination and Immunisation
- Vaccination refers to the act of administering a vaccine, while immunisation is the overall process of becoming immune to a disease.
- Vaccines stimulate the immune system to protect against subsequent infections or diseases.
Importance of Immunisation
- Immunisation is a crucial method of primary prevention of infectious diseases.
- It is a key component of primary health care and a vital aspect of the human right to health.
- Immunisation programs contribute to global health security and are highly cost-effective health interventions.
- Immunisation has led to a reduction in the incidence and complications of communicable diseases, lowering mortality and morbidity rates.
- Examples of benefits include:
- Prevention of meningitis in children through Haemophilus influenza B vaccine (pre-exposure prophylaxis).
- Protection against rabies after a dog bite (post-exposure prophylaxis).
- Immunisation plays a role in cancer prevention, such as liver cancer through Hepatitis B vaccination and cervical cancer through HPV vaccination.
- Herd immunity protects even unvaccinated individuals when a significant portion of the population is immune.
- Immunisation programs are highly cost-effective and promote economic development.
- Immunisation contributes to disease eradication (e.g., smallpox) and elimination (e.g., polio).
- It facilitates safe travel and mobility.
- Immunisation strengthens education and women's empowerment as a component of maternal and child health programs.
- Immunisation serves as a cornerstone of primary healthcare, building infrastructure and capacity.
- It promotes equity, benefiting disadvantaged populations who disproportionately suffer from communicable diseases.
Types of Vaccines
- There are two main vaccine types:
- Whole microbe vaccines: Live attenuated or inactivated (killed) vaccines.
- Component vaccines: Contain specific parts of a microbe, such as toxoids, subunits, virus-like particles, outer membrane vesicles, viral vectored, and nucleic acid vaccines.
- Viral vector and nucleic acid vaccines are newer vaccine types with potential applications.
Monovalent, Polyvalent, and Combination Vaccines
- Monovalent vaccines target a single strain of a single antigen (e.g., measles vaccine).
- Polyvalent vaccines target two or more strains of the same antigen (e.g., oral polio vaccine).
- Combination vaccines contain multiple antigens in a single injection, preventing various diseases or offering wider protection against a single disease.
Forms of Vaccine Administration
- Vaccines can be administered through various routes, including:
- Oral
- Subcutaneous
- Intramuscular
- Intradermal
- Intranasal
National Immunisation Programs (NIPs)
- NIPs are organizational units within ministries of health that aim to prevent disease, disability and death from vaccine-preventable diseases.
- Every country has a NIP to protect its population.
- Australia's NIP: Established in 1997, it aims to increase national immunisation coverage and decrease vaccine-preventable diseases.
Immunisation Coverage and Vaccine Efficacy
- Immunisation coverage: Percentage of children who receive recommended vaccines.
- It measures the performance of immunisation systems. Global coverage has improved over the past decade.
- DPT3 (diphtheria, tetanus, pertussis) is a common indicator of immunisation coverage worldwide.
- Vaccine efficacy indicates how well a vaccine protects individuals from disease, compared to a placebo.
- Vaccine effectiveness measures how well a vaccine performs in real-world settings, observing its impact on the entire population.
Legal and Ethical Aspects of Vaccination
- Compulsory vaccination is often implemented to achieve high vaccination rates and protect against infectious diseases.
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Australia's legislation:
- No jab, no pay (and play): Withholds childcare benefits for parents who do not fully vaccinate their children.
- Mandates vaccination or medical exemption for children attending childcare centres.
- Requires parents to provide an ongoing immunisation history statement to maintain enrolment.
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Ethical considerations:
- Mandates can infringe on individual autonomy and liberty, posing challenges for religious communities.
- Inequities in access to vaccines: Socioeconomic and racial/ethnic minority groups often face barriers in accessing vaccination, especially low-income children and those without health insurance.
Herd Immunity
- Herd immunity: Indirect protection from contagious diseases due to a high proportion of immune individuals in a population.
- Threshold level: The minimum percentage of immune individuals required to prevent outbreaks, varying based on disease transmissibility and severity.
- Basic reproduction number (R0): The average number of people a single infected person can transmit a disease to in an unprotected population. Diseases with higher R0 are more contagious and require a higher herd immunity threshold.
Vaccine-Preventable Disease (VPD) Outbreaks
- VPD outbreaks are a major public health concern requiring prompt and effective responses.
- Recent examples include pertussis in Australia, polio in Indonesia, measles in Europe, and diphtheria, measles, and pertussis outbreaks in Malaysia.
- Key steps in VPD outbreak investigations include:
- Verifying the diagnosis and confirming the outbreak.
- Establishing a case definition.
- Case finding and data collection.
- Describing the outbreak's characteristics (age, location clusters, vaccine coverage).
- Generating and testing hypotheses about the outbreak's cause.
- Implementing control and prevention measures, including vaccination.
- Analyzing the event and communicating findings.
Monitoring and Surveillance of VPDs
- Surveillance is crucial for guiding vaccination programmes and achieving immunisation targets.
- Passive surveillance: Regular reporting of disease data from healthcare facilities. The most common method used to detect VPDs.
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Active surveillance: Visits to healthcare facilities, discussions with providers, and review of medical records to identify suspected VPDs.
- Used for eradication/elimination programs and during outbreaks.
- Syndromic surveillance: Identifies clusters of illness based on syndromes (e.g., respiratory or gastrointestinal illness) before diagnoses are confirmed, enabling rapid response.
- Australia: The following VPDs are under mandatory notification: Measles, mumps, diphtheria, pertussis, tetanus, rotavirus, varicella zoster, Haemophilus influenzae B, rubella, poliomyelitis, influenza, meningococcal disease (invasive), and pneumococcal disease (invasive).
Globalisation and Vaccination
- Increased trade and travel have accelerated disease transmission across borders.
- Vaccination plays a crucial role in ensuring safe travel and preventing communicable diseases from reaching non-endemic regions.
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Australia:
- Routine vaccinations: Recommended for all travellers regardless of destination, including those for hepatitis B, measles, mumps, rubella, varicella, pertussis, poliomyelitis, tetanus, and diphtheria.
- Required vaccinations: Mandatory for entry into certain destinations (e.g., yellow fever for Africa and South America, meningococcal disease for pilgrims travelling to Mecca).
- Recommended vaccinations: Medically advised based on the traveller's itinerary and specific disease risks, including cholera, Japanese encephalitis, rabies, hepatitis A and B, and typhoid fever.
Challenges to Effective Immunisation
- Vaccine hesitancy: Reluctance or refusal to vaccinate despite availability.
- Equitable access to vaccines: Disparities in vaccination coverage across regions and populations.
- Emerging and reemerging diseases: Novel or resurgent infectious diseases.
Vaccine Hesitancy
- Vaccine hesitancy is a significant threat to progress in controlling VPDs.
- It leads to disease resurgences, as seen with the 30% global increase in measles cases.
- Causes of vaccine hesitancy include: complacency, inconvenience accessing vaccines, and lack of confidence.
- Anti-vaccine campaigns: Concerns about vaccine safety, particularly after the publication of a study linking the MMR vaccine to autism in 1998 (later retracted).
- COVID-19 pandemic: Declining confidence in childhood vaccines after the pandemic.
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Parental positions on vaccines:
- Unquestioning acceptors
- Cautious acceptors
- Hesitant vaccinators
- Late/selective vaccinators
- Refusers
Equitable Vaccine Access
- 14.3 million infants worldwide did not receive their initial DTP dose, and 6.2 million only partially vaccinated.
- Low- and middle-income countries: Face disproportionately low immunisation coverage due to lack of parental education, low incomes, poor access to healthcare facilities, and traditional beliefs.
- Conflict-affected areas: 14 out of 16 conflict-affected countries have immunisation coverage below the global average for diphtheria, pertussis, and tetanus (85%). Six of these countries have coverage below 50%.
- Challenges in conflict zones: Destruction of healthcare facilities, lack of essential infrastructure, security concerns for healthcare workers, shortage of medical professionals, and difficulties for refugees to access vaccines.
Emerging and Re-emerging Diseases
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Emerging infectious diseases: Newly identified diseases or known diseases rapidly increasing in frequency or geographic range.
- Examples: Dengue, West Nile virus, Zika, COVID-19.
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Re-emerging diseases: Diseases reappearing after significant decline.
- Examples: Tuberculosis, cholera, pertussis, influenza.
- WHO has identified high-priority pathogens: Chikungunya, streptococcus A and B, herpes simplex virus, malaria, respiratory syncytial virus (RSV), and tuberculosis.
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Challenges of vaccine development:
- A lengthy and complex process with many steps where failure is possible at any stage.
- Requires significant research investment.
- Efficacy evaluation is challenging in outbreak settings due to disruptions and social disorder.
- Low immunisation rates can contribute to the re-emergence of VPDs.
Conclusion
Vaccination rates, health systems, and health determinants are interconnected. Ongoing safety monitoring is crucial. While vaccines are generally safe and effective, there are known side effects. For example, the 2010 influenza vaccine was associated with an increased risk of fever and febrile convulsions in children.
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Description
This quiz covers the fundamental concepts of vaccination and immunisation, emphasizing their importance in preventing infectious diseases. Learn about the processes involved and the impact of immunisation programs on global health security and cost-effectiveness.
