The astrology of past pandemic/plagues is mixed. Finding a start date is tricky so what is below should be taken with a pinch of caution.
Most obvious was the Black Death of 1347-51 when outbreaks of Yersinia pestis Bubonic plague in Europe killed 30%-60% of the population, circa 100 million. It appeared to come from the east. French surgeon Guy de Chauliac suggested the March 1345 Solar Eclipse was to blame. At that point the Solar Eclipse was in late Pisces; with Mars Saturn Jupiter and Neptune in Aquarius. There was also a Uranus Pluto conjunction in Aries which caught the following Total Lunar Eclipse. That is a fairly classic signature with Saturn conjunct Neptune and a disruptive Uranus Pluto.
The Justinian Plague of AD 541/2, one of the deadliest pandemics in history, resulted in the deaths of an estimated 25–100 million people during two centuries of recurrence. It was similar to the Black Death and also came from the east. Neptune in Pisces was opposition Uranus and trine Saturn; with Uranus trine Pluto.
A prominently aspected Neptune occurs in many though not all instances of plagues. It isn’t much in evidence at the moment.
The Antonine Plague AD 165 was brought back from Roman troops returning from the east, thought to be measles or smallpox-related with a 25% mortality rate. Neptune in Scorpio was opposition Pluto and trine Uranus; with Pluto trine Saturn.
Neptune Pluto is devastating, often found alongside natural disasters; Neptune Uranus is highly-strung and anxious; Pluto Saturn is hardship.
The Plague of Athens 430BC, a typhoid-like plague kills up to a third of Athenians. Saturn in Scorpio was square Pluto and square Uranus; with the Uranus Pluto conjunction in Aquarius having occurred two or three years before. Neptune in Aries sextile Pluto.
Great Plague of London 1665. Another bout of the Bubonic plague which wiped out nearly a quarter of all Londoners and was followed by the Great Fire of London in 1666. Both Saturn and Neptune were in Capricorn; Uranus in Aquarius was trine Pluto in Gemini.
The Third Plague Pandemic in 1855 another bubonic plague outbreak starting in China and leading to more than 12 million deaths in India and China, with about 10 million killed in India alone. Neptune in Pisces squared Saturn in Gemini. Pluto and Uranus were both in Taurus.
Russian flu 1889-90, spread through the northern hemisphere in four months, claiming one million lives. Neptune was in a devastating conjunction to Pluto in Gemini; Saturn in Leo and Uranus in Libra.
Spanish flu 1918-19, kills at least 50 million people and infects a third of the world’s population. Saturn Neptune conjunct in Leo, Pluto in early Cancer and Uranus in late Aquarius.
Asian flu 1957-58, kills 1-2 million people worldwide. A vaccine is rapidly developed. Neptune in early Scorpio square Uranus, Saturn in Sagittarius and Pluto in late Leo.
SARS 2002-03, a form of coronavirus infects 8,096 people and causes 774 deaths — a mortality rate of almost 10%. The bleak Pluto in Sagittarius opposition Saturn is waning; as is the Uranus Neptune conjunction in Aquarius.
This is all a touch ghoulish but at least there’s hope nowadays of a vaccine appearing sometime and conditions aren’t as terrifying as they must have been during these earlier plagues.