If COVID originated from bats or whatever, then the reason we don’t see multiple viruses going around simultaneously is because animal–human crossover, though i

If COVID originated from bats or whatever, then the reason we don’t see multiple viruses going around simultaneously is because animal–human crossover, though it certainly does happen, happens more rarely than that. If COVID is a virus of whatever origin that escaped from a Chinese lab (only mentioning this because it’s a popular theory among ordinary netizens and the WHO expressly didn’t rule it out, though it called it not a likely scenario), then we don’t see multiple pathogens going around the world because all developed countries’ top-security bio labs are – thankfully – quite secure. Stephen King’s The Stand and Richard Preston’s The Hot Zone have kept readers awake at night with fear for decades now, but the labs they describe have managed to keep their pathogens from escaping. Also, some horrible pandemics of yore like bubonic plague were easy to stamp out by modern hygiene practices, which is why they only pop up today in undeveloped places with poor hygiene (e.g. prisons in Madagascar).