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Challenge 1: Comparing COVID-19 Outbreaks

Learning Targets:

  • Differentiate between a pandemic and epidemic.
  • Analyze and interpret epidemiological data.
  • Perform calculations in order to accurately compare data.
  • Identify and use credible sources to find data to support a conclusion.

The story continues...

On an early Friday morning, everyone on the crowded bus is buzzing with excitement for the coming weekend, including high schooler juniors Tash, Ray, and June. As Ray and June argue over who’s plans for the weekend will be more exciting, Tash sits quietly between his friends, feeling unusually hot and uncomfortable. Upon arriving at school, the trio heads to the nurse’s office, where the nurse informs Tash that he has a fever and warns them about an outbreak of COVID-19 in New Haven. Worried about an outbreak in their community, Tash, Ray, and June google “COVID-19” and find out that it is being called a “pandemic.” But what exactly is a pandemic, and how is a disease classified as a pandemic? What is R0? Activities in the challenges below will lead to the answer and more about pandemics.


Reflect & Discuss:

Both pandemics and epidemics involve outbreaks of diseases, but what is the difference between a pandemic and an epidemic?

Read on:

image: june

“So what did the article say?” Carla asks June referencing the news alert that popped up on her phone a few minutes ago.

“Oh, it is a report about how COVID-19 outbreaks are different in countries across the world. It describes how case numbers and death rates vary,” June says.

“But when I look at this chart, it seems confusing, because the numbers are all over the place. Like the article says that the current outbreak in Peru is much worse than the outbreak was in Italy, but the numbers don’t make much sense to me.”

“Numbers aren’t always presented in a way that allows you to compare them. It’s important to make sure you are comparing apples to apples. Let’s look at it together, “ Carla suggests, suddenly willing to use her new expertise.

Table 1. Confirmed COVID -19 cases and mortality for five selected countries. Number of people with confirmed cases of COVID -19 and number of COVID -19 associated deaths by country1.

Country Confirmed Cases Deaths
Germany 191,768 8,899
Italy 238,720 34,657
China 84,624 4,639
Peru 257,447 8,223
United States 2,312,302 120,402

1As of June 23, 2020 3:00 AM EDT, Johns Hopkins University Coronavirus Resource Center

“Ah, I see what’s happening here. They are only presenting the total case number and that doesn’t say much,” Carla declares. “You can’t tell from that data how big the outbreak is in each country.”

“Okay, but which of these countries has the biggest outbreak?” Ruben asks

Reflect and Discuss:

What additional information do you need to know in order to answer Ruben’s question? Hint: “big” is a relative term.

Read on:

image: june

“We learned in school this year that in order to validly outbreak sizes, epidemiologists normalize the numbers so you can compare them.” Carla details further, “you can represent the case number as per 100,000 people in a population. "Remember, the population is the number of people who live in a country.”\

Ruben asks, “Do we have the information needed for this calculation? Where could we find it? How could we represent that information on our table?”


  • Find the information needed to answer Ruben’s questions.

Calculate and Represent on Table:

  • Determine the number of cases per 100,000 people in a population (case/100k pop) for each country listed in Table 1 on June 23, 2020.

Conclude and Discuss:

  • On June 23, 2020, which country had the highest case/100k pop? The lowest?

Read on:

image: june

“Oooooh!” June exclaims as the concept seems to click. “The numbers of deaths also can’t be compared. It really makes more sense to look at the number of deaths relative to the number of cases in a country.”

“Yes, June, that’s exactly right!” Carla says enthusiastically. “You can make a ratio from these two values.”

Calculate and Represent on Table:

  • Determine the fatality-case ratio on June 23, 2020 for each country (expressed as a percentage).

Conclude and Discuss:

  • Which country had the highest fatality-case ratio on June 23, 2020? The lowest?
image: june “That makes total sense now.” Ruben says. “Want a slice of bread?”

Reflect & Discuss



  • Based on your above calculations, decide which country has the biggest outbreak?

Consider population size, case number, or number of deaths. Which is most important when making this decision? You will need to define the word “big.”

  • Why do you think that the case-to-death ratios vary so much by country?

For instance, Germany’s ratio is very low and Italy’s is very high. What variables contribute to this discrepancy?