How is COVID-19 different from seasonal flu? [WIP]

[mikkokotila]

Background

Infectious disease can be readily compared through their "five legs":

• Prevention
• Spreading
• Symptoms
• Treatment
• Mortality

Comparison

Prevention

• Medical prevention for seasonal flu is commonplace
• There is no medical prevention for COVID-19
• There is extensive surveillance infrastructure for seasonal flu
• There is little to none surveillance infrastructure on COVID-19
• Extensive data is available for seasonal flu
• There is little to none available data on COVID-19
• There are decades of scientific literature on seasonal flu
• There is little to none scientific literature on COVID-19

Spreadings

• R0 (basic reproduction number) of seasonal flu is ~1.5
• R0 of COVID-19 is 2-3
• For example, an R0 of 2 means that every person with the infection will spread it 2 to two other people
• In a 1 to 4 month window, COVID-19 will infect 200x more people than seasonal flu, everything else being the same

Symptoms

• Seasonal flu does not have a strong connection with pneumonia
• And even if seasonal leads to pneumonia, then it is with the older population
• COVID-19 is basically pneumonia, only some are asymptomatic so they do not develop it
• COVID-19 can lead to pneumonia to a younger population
• If you are hospitalized because of seasonal flu, you have a 0.5% chance to develop ARDS
• If you are hospitalized because of COVID-19, you have between 17% and 29% chance to develop ARDS
• If you get ARDS because of seasonal flu, the onset is typically gradual
• If you get ARDS because of COVID-19, the onset is rapid

Treatment

• There are many treatments available for seasonal flu
• Seasonal flu very rarely requires treatment
• COVID-19 has no known treatments
• COVID-19 regularly requires treatment
• In a dataset of spanning 10 years and 60,000 ICU admissions, there are 187 seasonal flu ICU admissions in total
• Currently, in late March 2020, a single hospital can see more COVID-19 ICU admissions in two weeks

Mortality

• Seasonal flu has a mortality rate of ~0.1%
• COVID-19 seems to have a mortality rate closer to ~5%

NOTE: here the comparison may not be entirely honest; COVID-19 reflects mostly hospitalized patients.