PPH4813
ASSIGNMENT 2
DUE DATE: 15 MAY 2026
, PPH4813 ASSIGNMENT 2 2026
DUE 15 MAY 2026
1. Describe the following epidemiology terms in relation to Rubella
Rubella (German measles) is a vaccine-preventable disease that illustrates key
epidemiologic concepts (CDC, Lesson 1, pp. 1-2).
1.1 Herd immunity
Herd immunity is the indirect protection of a population when a high proportion of
individuals are immune to an infection, thereby reducing the likelihood of transmission
(Merrill, 2017, Chapter 3, p. 54). For rubella, the herd immunity threshold is estimated at
83–85% (CDC, Lesson 1, p. 55). This protects pregnant women and others who cannot
be vaccinated.
1.2 Outbreak
An outbreak is an epidemic limited to a localised increase in disease incidence (CDC,
Lesson 6, p. 3). A rubella outbreak would be a sudden increase in cases in a specific
school or community above expected levels.
1.3 Epidemic
An epidemic is the occurrence of more cases of disease than expected in a given area
or among a specific group over a particular time period (Merrill, 2017, Chapter 1, p. 5).
Widespread rubella in a region, such as the 1964-1965 U.S. epidemic, is an example.
ASSIGNMENT 2
DUE DATE: 15 MAY 2026
, PPH4813 ASSIGNMENT 2 2026
DUE 15 MAY 2026
1. Describe the following epidemiology terms in relation to Rubella
Rubella (German measles) is a vaccine-preventable disease that illustrates key
epidemiologic concepts (CDC, Lesson 1, pp. 1-2).
1.1 Herd immunity
Herd immunity is the indirect protection of a population when a high proportion of
individuals are immune to an infection, thereby reducing the likelihood of transmission
(Merrill, 2017, Chapter 3, p. 54). For rubella, the herd immunity threshold is estimated at
83–85% (CDC, Lesson 1, p. 55). This protects pregnant women and others who cannot
be vaccinated.
1.2 Outbreak
An outbreak is an epidemic limited to a localised increase in disease incidence (CDC,
Lesson 6, p. 3). A rubella outbreak would be a sudden increase in cases in a specific
school or community above expected levels.
1.3 Epidemic
An epidemic is the occurrence of more cases of disease than expected in a given area
or among a specific group over a particular time period (Merrill, 2017, Chapter 1, p. 5).
Widespread rubella in a region, such as the 1964-1965 U.S. epidemic, is an example.
