Vaccines and Vaccination

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Questions and Answers

What does VE represent in the formula for vaccine efficacy?

Viral escape

Vaccine efficiency

Vaccine effectiveness

Vaccine efficacy (correct)

Which type of vaccine is developed using molecular based technologies?

Killed/inactivated vaccines

Live-attenuated vaccines

Component vaccines

Chimeric organism vaccines (correct)

Which of the following is NOT a type of vaccine?

Recombinant-vector vaccines

Nucleic acid vaccines

Toxoid vaccines

Etaples vaccines (correct)

What is the formula used to calculate vaccine efficacy?

VE = (ARU - ARV) / ARU Signup and view all the answers

What is the term used to describe the reduction in disease attack rate between unvaccinated and vaccinated individuals?

Vaccine efficacy Signup and view all the answers

What is the purpose of adjuvants in vaccine development?

To enhance the immune response to an antigen Signup and view all the answers

What type of vaccine involves the use of a plasmid containing a gene for a target antigen?

DNA vaccine Signup and view all the answers

What is the main difference between a live vector vaccine and a recombinant organism vaccine?

The vector used to deliver the antigen Signup and view all the answers

What is the goal of the DIVA vaccine?

To differentiate infected from vaccinated animals Signup and view all the answers

What type of vaccine involves the use of a virus incapable of causing disease in the host?

Recombinant organism vaccine Signup and view all the answers

What is the difference between a DNA vaccine and an mRNA vaccine?

The method of antigen expression Signup and view all the answers

What is the role of dendritic cells in DNA vaccines?

To present the antigen to lymphocytes Signup and view all the answers

What is the purpose of cloning a gene for an immunogenic protein in vaccine development?

To develop a recombinant organism vaccine Signup and view all the answers

What is the primary difference between passive and active immunization?

The administration of antibodies versus antigens Signup and view all the answers

What is the result of active immunization?

Induces an immune response and immunological memory Signup and view all the answers

What is the primary advantage of active immunization over passive immunization?

Induction of immunological memory Signup and view all the answers

What is the result of vaccination in terms of disease eradication?

Reduction in disease incidence Signup and view all the answers

What is the role of adjuvants in vaccine development?

To enhance the immune response Signup and view all the answers

What is the primary concern regarding vaccine adverse events?

Risk of adverse events outweighing the benefits of vaccination Signup and view all the answers

What is the significance of the concept of vaccine efficacy?

Measuring the effectiveness of a vaccine in preventing disease Signup and view all the answers

What does specificity measure?

The proportion of true negatives among all actual negatives Signup and view all the answers

What is the formula for calculating sensitivity?

TP / (TP + FN) Signup and view all the answers

What is the primary significance of predictive values in clinical practice?

They indicate the probability of a test result being correct Signup and view all the answers

What is the positive predictive value of a test?

The probability of a positive test being a true positive Signup and view all the answers

What is the primary difference between prevalence and incidence?

Prevalence measures existing cases, while incidence measures new cases Signup and view all the answers

What is the impact of prevalence on predictive values?

It has a strong impact on predictive values Signup and view all the answers

What is the purpose of a test predictive value?

To determine the probability of a test result being correct Signup and view all the answers

What is the negative predictive value of a test?

The probability of a negative test being a true negative Signup and view all the answers

What is the primary purpose of diagnostic tests in veterinary medicine?

To confirm or exclude a diagnosis and inform treatment decisions Signup and view all the answers

What is the phase of testing that involves handling and analysis of the specimen?

Analytical Signup and view all the answers

What is the term used to describe a test result that is classified as positive when the patient is actually diseased?

True Positive Signup and view all the answers

What is the consequence of using inadequate samples in diagnostic testing?

Inadequate results Signup and view all the answers

What is the term used to describe the ability of a test to detect true positive results?

Sensitivity Signup and view all the answers

What is the phase of testing that involves report results and interpretation?

Post-analytical Signup and view all the answers

What does diagnostic sensitivity measure?

The capacity of a test to correctly identify the positive individuals Signup and view all the answers

What is the primary factor that determines the selection of a diagnostic test?

Type of pathogen Signup and view all the answers

What is the consequence of a false negative test result?

Delayed diagnosis and treatment Signup and view all the answers

What is the formula for calculating diagnostic specificity?

TN / (TN + FP) × 100 Signup and view all the answers

What happens to the sensitivity of a test when the cut-off value is decreased?

Sensitivity increases and specificity decreases Signup and view all the answers

What is the formula for calculating Positive Predictive Value (PPV)?

TP / (TP + FP) Signup and view all the answers

What is the consequence of increasing the cut-off value of a test?

More false negatives and fewer false positives Signup and view all the answers

What is the formula for calculating Sensitivity?

TP / (TP + FN) Signup and view all the answers

What is represented by the abbreviation TP in a diagnostic test?

True Positive Signup and view all the answers

What is the purpose of calculating Negative Predictive Value (NPV)?

To determine the proportion of true negatives among all negative test results Signup and view all the answers

What is the formula for calculating Accuracy?

(TP + TN) / (TP + FN + TN + FP) Signup and view all the answers

What is the purpose of calculating diagnostic sensitivity and specificity?

To determine the accuracy of a test Signup and view all the answers

What is the term for the proportion of true positives among all diseased individuals?

Sensitivity Signup and view all the answers

What is the term for the proportion of true negatives among all non-diseased individuals?

Specificity Signup and view all the answers

What is the formula for calculating Specificity?

TN / (TN + FP) Signup and view all the answers

What is the significance of prevalence in calculating Positive Predictive Value (PPV)?

Prevalence increases PPV Signup and view all the answers

Study Notes

History of Immunization

15th century China: Variolation, where individuals who recovered from smallpox never suffered from it again, led to deliberately infecting children with smallpox through dried scabs, resulting in local disease with lower mortality.
1700s: Variolation spread to England.
1796: Edward Jenner discovered that infection with cowpox protected against smallpox, leading to the first vaccine.
Louis Pasteur developed vaccines for Pasteurella multocida (1879), Anthrax (1881), and Rabies (1885).

Types of Immunization

Passive Immunization: administration of preformed antibodies specific to a particular antigen, providing immediate but short-lived protection with no immunological memory.
Active Immunization: administration of antigens, inducing an immune response and immunological memory, and is the most common form of immunization.

Types of Vaccines

Live-Attenuated Vaccines: contain weakened pathogens, providing long-term immunity.
Killed/Inactivated Vaccines: contain inactivated pathogens, providing short-term immunity.
Subunit Vaccines: contain small components of pathogens, providing short-term immunity.
DIVA Vaccines: allow differentiation between infected and vaccinated animals.
Nucleic Acid Vaccines: contain DNA or mRNA, generating an immune response.
Recombinant Organism Vaccines: use a vector to express immunogenic proteins.

Adjuvants

Substances that enhance or facilitate an immune response to an antigen.

Vaccine Efficacy

Expressed as a reduction in disease attack rate between unvaccinated and vaccinated individuals.
Can refer to different outcomes, such as death, severe disease, clinical disease, or infection, with varying efficacies for each outcome.

History of Vaccine Development

Early vaccines: Live-attenuated, Killed/Inactivated, and Component vaccines.
Modern vaccines: Molecular-based technologies, Chimeric organisms, Recombinant subunit vaccines, Nucleic acid vaccines, Virus-like particles, and Reverse vaccinology.

Importance of Diagnostic Tests

Confirm or exclude a diagnosis
Determine treatment strategies
Epidemiological surveillance
Prevention, control, and eradication strategies
Identification of new pathogens

Phases of Testing

Pre-analytical: test selection, sampling, storage, transportation
Analytical: handling and analysis of the specimen
Post-analytical: report results, interpretation

Test Selection

Determined by type of pathogen, type of sample, test characteristics, phase of disease, availability, and cost

Sample Considerations

Samples must be correctly selected, collected, stored, and transported
Inadequate samples result in inadequate results

Understanding Test Results

Results can be divided into 4 categories: true positive, false positive, false negative, true negative
Cut-off value divides results between positive or negative

Diagnostic Sensitivity and Specificity

Sensitivity: measures the capacity of a test to correctly identify positive individuals (true positives)
Specificity: measures the capacity of a test to correctly identify negative individuals (true negatives)
Equations: sensitivity = (TP / TP + FN) × 100, specificity = (TN / TN + FP) × 100

Impact of Cut-off Change

Increase sensitivity, decrease specificity
Decrease sensitivity, increase specificity

Test Predictive Value

Positive Predictive Value (PPV): probability of a positive test being a true positive
Negative Predictive Value (NPV): probability of a negative test being a true negative
Equations: PPV = (TP / TP + FP) × 100, NPV = (TN / TN + FN) × 100

Prevalence

Proportion of a population affected by a disease at a specific time
Not to be confused with incidence, which refers to the number of new cases in a time interval

Impact of Prevalence on Predictive Values

PPV and NPV are affected by prevalence, diagnostic sensitivity, and specificity

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Description

Learn about the history of immunization, types of vaccines, passive and active immunization, vaccine efficacy, adjuvants, and vaccine adverse events. Understand the concepts and advantages of different types of vaccines.