group <- c("Vaccinated", "Unvaccinated")
cases <- c(5, 25)
population <- c(500, 500)
risk <- cases / population
barplot(
risk,
names.arg = group,
col = c("steelblue", "tomato"),
main = "Risk of Infection by Vaccination Status"
)
Measures and Data
Key Concept
Important
Vaccine effectiveness measures the reduction in disease risk among vaccinated individuals compared to unvaccinated individuals in real-world conditions.
Step-by-Step Calculation
Show calculation
Calculate risk in the vaccinated group: 5 / 500 = 0.01
Calculate risk in the unvaccinated group: 25 / 500 = 0.05
Relative Risk = 0.01 / 0.05 = 0.2
VE = (1 − 0.2) × 100 = 80%
Pause and Reflect
TipSelf-check
Why might vaccine effectiveness differ between populations?
Show suggested answer
Differences in exposure, population structure, healthcare access, and underlying health conditions can influence estimates.
Youtube
Panopto
R Code Demos R Code and Output
R Code Only
group <- c("Vaccinated", "Unvaccinated")
cases <- c(5, 25)
population <- c(500, 500)
risk <- cases / population
barplot(
risk,
names.arg = group,
col = c("steelblue", "tomato"),
main = "Risk of Infection by Vaccination Status"
)R Output Only
Interactive R Code
R Code Table example
Interpreting the Results
An 80% vaccine effectiveness means vaccinated individuals have substantially lower risk compared to unvaccinated individuals.
The calculation assumes both groups are comparable and equally exposed.
Confounding factors such as age, immunity, or healthcare access may influence results.
Epidemic Curve
Outbreak Report
Download Dataset
Quiz
Based on the outbreak data, what does a vaccine effectiveness of 80% mean in practice?
Show answer
Answer: Vaccinated individuals have an 80% lower risk of infection than unvaccinated individuals
Explanation:
Vaccine effectiveness compares the risk of disease in vaccinated and unvaccinated groups under real-world conditions. An 80% VE means the vaccinated group experienced substantially lower risk, not that infection risk was eliminated entirely.
Key Takeaway
Tip
Vaccination significantly reduces the likelihood of infection and severe disease, even if it does not eliminate risk entirely.
Binomial Theorem equation
\[(x + a)^{n} = \sum_{k = 0}^{n}{\binom{n}{k}x^{k}a^{n - k}}\]
Latex Equations Approach
Display equation example
\[ P(X=x)=\binom{n}{x}p^x(1-p)^{n-x} \]