COVID-19 in Context

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How does the 2019 novel coronavirus disease (COVID-19) epidemic compare in severity to other recent disease outbreaks? We gathered data from existing studies to put COVID-19 into context.

The figures below illustrate variability both among and within recent outbreaks of zoonotic pathogens, including:

• The current outbreak of COVID-19
• The 2012-2015 Middle East outbreak of MERS (Middle East respiratory syndrome)
• The 2015 South Korea outbreak of MERS
• The 2003 SARS (severe acute respiratory syndrome) pandemic
• The 2014-2016 West Africa outbreak of Ebola virus disease
• The 2009-2010 H1N1 influenza pandemic
• The 1957 H2N2 influenza pandemic
• The 1918 H1N1 influenza pandemic

We compare these outbreaks using key epidemiological parameters, such as:

• The basic reproduction number (\(R_0\))
• Incubation period
• Infectious period
• Serial interval
• The proportion of cases characterized by various disease outcomes

For detailed information on the estimates presented below and their original sources, click here.

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How infectious is COVID-19?

Estimates of the basic reproduction number (\(R_0\)): the average number of new infections that are caused by one infectious person, assuming the whole population is susceptible. This value can differ based on setting, e.g. it is likely higher in more crowded places, or can vary between children and adults.

How long does it take to develop symptoms?

Estimates of incubation period: the number of days between pathogen exposure and the onset of symptoms.

How long can infected patients spread the virus?

Estimates of the infectious period: the number of days over which an infected individual is able to transmit the virus. This might or might not be the same as the symptomatic period.

How quickly does transmission occur?

Estimates of the serial interval: the number of days between the onset of symptoms in one case and the onset of symptoms in a subsequent case.

What percent of infected cases result in…?

No Symptoms

Estimates of the percent of individuals who are asymptomatic.

Fever

Estimates of the percent of infected patients that present with a fever.

Cough

Estimates of the percent of infected patients that present with a cough.

Death

Estimates of the percent of infected patients that die from their illness.

What percent of symptomatic cases result in…?

Fever

Estimates of the percent of symptomatic patients that present with a fever.

Cough

Estimates of the percent of symptomatic patients that present with a cough.

Death

Estimates of the percent of symptomatic patients that die from their illness.