Mary Shelley Part Four: THE LAST MAN
This work appeared in 1826, with the writer being described simply as "The Author of Frankenstein." The setting is England in the early 2070s. It is now a republic with a Lord Protector and a unicameral assembly. Apart from that, this England is very similar to 1820s England, with horse-drawn vehicles as the main mode of transport. However, there is air-travel, by winged, dirigible balloon.
The book takes quite a while to get going, as would be expected for a work of its time and the real story does not begin until the Greeks are besieging the city of Constantinople. There, a mysterious plague is encountered for the first time and the war is brought to an immediate halt as both armies retreat.
The description of the progress of the pandemic is eerily reminiscent of recent events, with the disease being at first underestimated as a passing problem. But gradually more and more countries are infected with terrible loss of life. The hero and his family escape doomed England, heading for Switzerland which they hope the pandemic has not reached, but their numbers are constantly whittled down. Eventually, there are only 4 people left and the pandemic seems to have burned itself out. But this being Shelley, one dies of typhus and two others are drowned, leaving the narrator as The Last Man.
He resolves not to die quietly but sets out to sail the world until some natural event claims him.
Although the pandemic appears to be a natural disaster, there are two passages in the book which refer to strange atmospheric/astronomical phenomena; one being related to the Narrator and one being actually observed by him.
The meaning of these events is not revealed but there remains the possibility that the pandemic is of extraterrestrial origin.
As far as I know, this is the first story about humanity being exterminated by a pandemic