If you're counting pandemics since 1891, I think any number between 6 and 13 is more defensible than the number 2.

Let me count again, while leaving out relatively minor pandemics like Zika:

* Fifth cholera pandemic

* Third plague pandemic (multiple outbreaks are listed)

* Sixth cholera pandemic

* 1915 encephalitis lethargica pandemic

* Spanish flu

* 1957-58 "Asian flu"

* Seventh cholera pandemic

* 1968-70 "Hong Kong flu"

* 1977 Russian flu

* HIV/AIDS pandemic

* 2009-10 swine flu

* COVID-19

That's 12 and doesn't count stuff like Zika, SARS, or MERS. It also doesn't count any of the Ebola epidemics.

I don't know if cases or deaths are a good proxy for expected supply chain impact. SARS, for instance, had relatively few cases and deaths because it mostly broke out in well-functioning developed East Asian countries that were capable of responding to it effectively, but those same countries have outsized effects on global supply chains.

It seems obvious to me that covid-19 had a much greater impact than any of those previous pandemics, even more severe ones, because it’s the first one for which we even attempted to implement such disruptive mitigations. Working from home was not feasible for most people in 1968-1970 for example, and nobody would have seriously suggested a major economic shutdown to deal with it.

An epidemic is an unexpected rise in cases within a community or region, which could mean part of a country, an entire country, an ethnic group spread across multiple countries, or an entire landmass. And a pandemic is an epidemic that has exponential growth.

An epidemic usually starts within a particular country and if it becomes a pandemic it will grow rapidly and spread to other countries, but the WHO definitions are only based on the number of cases compared to normal and how fast the number of cases is rising.