Perhaps the most important thing people should realize about such epidemics, is that the spread of the epidemic in any country endangers the entire human species. This is because viruses evolve. Viruses like the corona originate in animals, such as bats. When they jump to humans, initially the viruses are ill-adapted to their human hosts. While replicating within humans, the viruses occasionally undergo mutations. Most mutations are harmless. But every now and then a mutation makes the virus more infectious or more resistant to the human immune system – and this mutant strain of the virus will then rapidly spread in the human population. Since a single person might host trillions of virus particles that undergo constant replication, every infected person gives the virus trillions of new opportunities to become more adapted to humans. Each human carrier is like a gambling machine that gives the virus trillions of lottery tickets – and the virus needs to draw just one winning ticket in order to thrive .
This is not mere speculation. Richard Preston’s Crisis in the Red Zone describes exactly such a chain of events in the 2014 Ebola outbreak. The outbreak began when some Ebola viruses jumped from a bat to a human. These viruses made people very sick, but they were still adapted to living inside bats more than to the human body. What turned Ebola from a relatively rare disease into a raging epidemic was a single mutation in a single gene in one Ebola virus that infected a single human, somewhere in the Makona area of West Africa. The mutation enabled the mutant Ebola strain – called the Makona strain – to link to the cholesterol transporters of human cells. Now, instead of cholesterol, the transporters were pulling Ebola into the cells. This new Makona strain was four times more infectious to humans.
As you read these lines, perhaps a similar mutation is taking place in a single gene in the coronavirus that infected some person in Tehran, Milan or Wuhan. If this is indeed happening, this is a direct threat not just to Iranians, Italians or Chinese, but to your life, too. People all over the world share a life-and-death interest not to give the coronavirus such an opportunity. And that means that we need to protect every person in every country.
In the 1970s humanity managed to defeat the smallpox virus because all people in all countries were vaccinated against smallpox. If even one country failed to vaccinate its population, it could have endangered the whole of humankind, because as long as the smallpox virus existed and evolved somewhere, it could always spread again everywhere.