Year 9 Science · Unit 1 · Lesson 17
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Learning Goals
Read the graph
Estimated global deaths from major 20th–21st century pandemics
Data: WHO Global Health Observatory; Roser et al. (2021), Our World in Data
(a) Which pandemic shown in the graph caused the most deaths? How many times more deadly was it than COVID-19?
(b) HIV/AIDS and COVID-19 are both pandemics. Based on the data and your lesson, suggest ONE reason why HIV/AIDS has accumulated more deaths over time despite being less deadly per infection than the 1918 flu.
(c) The 2009 H1N1 pandemic had the same virus type as the 1918 Spanish flu, yet caused far fewer deaths. Using lesson content, suggest ONE reason for this difference.
Real-world context
In late 2019, a cluster of unusual pneumonia cases appeared in Wuhan, China, linked to a wet market selling live animals. Genomic sequencing revealed a novel coronavirus (SARS-CoV-2). By March 2020, the WHO declared COVID-19 a pandemic. The virus had reached every inhabited continent in approximately 80 days. In early 2021, wealthy nations including Australia, the UK, and the USA had vaccinated 15–30% of their populations, while sub-Saharan African nations had vaccinated less than 5% of theirs.
(a) Explain how zoonotic spillover may have allowed SARS-CoV-2 to jump from bats (or an intermediate host) to humans at a wet market. Use the term "zoonosis" in your answer.
(b) Identify TWO specific factors (from your lesson) that allowed COVID-19 to spread globally in just 90 days, and briefly explain how each factor contributed.
(c) When Africa had less than 5% vaccine coverage while wealthy nations were at 15–30%, what are TWO disease science consequences of this inequality for the whole world (not just Africa)?
1. Define the term "zoonosis" and give ONE example of a disease that originated as a zoonosis, naming the animal source.
2. Ebola has a higher case-fatality rate than COVID-19 but never became a global pandemic. Using lesson content, explain why.
Wrap Up
In one sentence, what was the main idea of this lesson?