Principles of Immunization in Practice

Principles of Immunization in Practice

• This presentation covers principles of immunization and vaccination programs.
• It discusses the uses of immunization, impact of vaccination, precautions, and contraindications.
• Vaccination programs in practice include sources of information, vaccination programs in Canada, and vaccine hesitancy.

Role of Immunization

• The role of immunization is categorized into pre-exposure and post-exposure strategies, focused on the individual and population levels.
• Pre-exposure strategies aim to prevent illness through measures like vaccination.
• Post-exposure strategies address situations where individuals have been exposed to a disease.

Passive Immunization

• Passive immunization involves administering pre-formed antibodies to boost a recipient's immunity.
• This approach offers immediate effects and provides short-term immunity.
• Examples include post-exposure treatment and administering immune globulins.

Passive Immunizing Agents

• Standard immune globulins (e.g., measles, Hep A) and specific immune globulins (e.g., Hepatitis B, Rabies, Tetanus, Varicella-Zoster) are passive immunizing agents.
• Antitoxins (or antisera) such as botulism antitoxin and diphtheria antitoxin are also part of this category.

Active Immunization

• Active immunization, also known as vaccination, uses vaccines.
• Vaccines administer all or part of a micro-organism to trigger an immune response.
• This method often provides longer-lasting immunity and is usually a pre-exposure measure.

Impact of Vaccination

• Vaccination's impact is highly positive given the drastic decrease in occurrences, such as tetanus, over time.

Effectiveness of Routine Immunization

• Immunization programs show significant reductions in infectious diseases like tetanus, documented in Canadian statistics from 1957-2008.
• The cost-effectiveness of various public health interventions is highlighted in a table measuring the cost per life-year saved.

Precautions & Contraindications

• Contraindications and precautions for vaccines exist.
• For live vaccines, significant immunosuppression and pregnancy are contraindications.
• Recent administration of other live vaccines and vaccine-specific factors should be considered.
• Anaphylaxis is another major precaution.

Conditions that are NOT Contraindications to Immunization

• Premature birth, breastfeeding, and concurrent antibiotic therapy aren't contraindications for inactivated vaccines.
• Conditions like common illnesses (unless accompanied by fever), allergies, and concerns about past reactions should be explored further or appropriately managed.

Vaccination Programs

• Vaccination programs are similar across Canada but may differ in timing or introduction of new vaccines.
• Population-specific vaccination programs exist.
• The schedule for these varies regionally.

Designing Vaccination Programs

• Effective vaccines need factors such as safety, sustained protection, stability, affordability, and ease of administration.
• Introduction costs, use/implementation feasibility, and program structure (distribution, records, and surveillance) contribute to cost-effectiveness.
• The focus of vaccination programs can be general-population based or targeted.

Surveillance of CD

• Surveillance of communicable diseases (CD) is an essential aspect of vaccine program effectiveness.
• Vaccine efficacy (phases 1 to 3) and program effectiveness (phase 4) are part of evaluations and research in vaccine programs.

Targeted Vaccination

• Risk groups (age, comorbidities) are prioritized for targeted vaccination.
• Post-exposure vaccination, situations combining risk exposure and disease, and responding to outbreaks are also targeted.

Adult Immunizations in NL

• General population adult vaccination focuses on influenza.
• Adults over 60 and at-risk populations receive pneumococcal and herpes zoster vaccines.
• Boosters such as Tdap are given to adults every 10 years and during pregnancy.

Travel Vaccinations

• Health Canada provides travel vaccination recommendations.
• These might not be covered by provincial programs and are region/activity-based.
• Requirements for entry into other countries (e.g., yellow fever) are important factors for travelers.

Vaccine Hesitancy

• Vaccine hesitancy is a topic of discussion around vaccination.
• Reasons for refusal/delay of vaccination include personal beliefs, safety concerns, and access-related issues.

Reasons why people refuse/delay vaccination

• Personal beliefs, the belief that natural immunity is better, or that healthy diets and lifestyles are sufficient reasons for not getting vaccinated.
• Safety concerns from media, social media, friends, and family.
• A desire for more information, or difficulty talking to a healthcare provider also contribute.
• Access limitations like distance, lack of transportation, or child care needs pose hurdles to vaccination for some people.
• Communication issues like language barriers and cultural preferences are significant factors.

Outbreak Investigation

• Confirm diagnosis and existence of an outbreak by defining cases, analyzing data, controlling measures, and communicating effectively.
• Case definitions, time period, and place of exposure are crucial components of outbreak investigations.

Epidemiology Triangle

• The agent, host, and environment interact in the epidemiology triangle.
• The agent is the causative microbe.
• The host's susceptibility depends on natural defense mechanisms, genetics, age, health status, and living conditions.
• The environment is anything affecting the agent and the host.

Infectious Disease Process/Chain of Infection

• This process (chain of infection) concerns how infectious diseases spread.
• It involves agent, reservoir, portals of entry/exit, and mode of transmission.
• The reservoir is the habitat for the infectious agent.
• Transmission can be direct (immediate transfer) or indirect (involving fomites, air, water, food, or vectors).

Tools for Communicable Disease Control

• Public health tools for communicable disease control include surveillance, vaccination programs, sanitation, one health, case management, and outbreak response.

Surveillance

• Surveillance involves ongoing scrutiny of all disease aspects relevant to effective control.
• Passive surveillance (mandatory physician and laboratory reports), active surveillance (public health investigation), immunization uptake and complications, and environmental monitoring (water, air) are crucial components.

Control Measures

• Control measures prevent new primary cases and further transmission of the infection.
• These include controlling the source, proportionate measures, reassessing effectiveness, hygiene, isolation/quarantine, and prophylactic medication.

Communication

• Communication includes informing affected individuals, the healthcare community, relevant authorities, and services involved, and the public.

When is an outbreak over?

• An outbreak is considered over when there are no new cases for a significant period (twice the incubation period), the source is contained, and transmission appears interrupted.

Source Investigation

• The investigation often involves retrospective cohort studies to identify, trace, and assess the risks linked with the source of an outbreak.