In the COVID-19 pandemic world, it is a bit too easy to imagine the plagues of ancient Rome. Plagues are often referenced in ancient literature and we can see calls to the gods for deliverance in ancient coins.
Trebonianus Gallus was Emperor from June 251 – August 253, during a time when Rome was enduring a pandemic. "Pandemic" is a 17th century term from Greek: pan (all) demos (people).
In 1666, the English physician Gideon Harvey used “Pandemick” interchangeably with “Epidemick” to mean a malignant disease that “do generally…haunt a Country”.
-The Lancet, Pandemic, 2009 
Trebonianus Gallus, reigned during a difficult period, and was not emperor for long. At first, he took as his co-emperor the son of his predecessor, Trajan Decius. After the death of Hostilianus, he elevated his own son, Volusianus, to emperor or Augustus. He was proclaimed emperor by the army and eventually deposed and murdered by his own troops.
Trebonianus Gallus, Image Source: Katie Chao and Ben Muessig, CC BY-SA 2.0, via Wikimedia Commons
According to tradition, Apollo was first recognized in Rome in 433 BC. A temple was constructed in Campus Martius in response to a plague. The temple to Apollo was dedicated in 431 BC. Foreign deities could not reside inside the city walls, so it was located just outside the Porta Carmentalis and just beyond the city-limits.
"The pestilence during that year afforded a quiet in other matters. A temple was vowed to Apollo for the health of the people. The duumvirs did much, by direction of the books, for the purpose of appeasing the wrath of heaven and averting the plague from the people; a great mortality however was sustained in the city and country, by the death of men and of cattle promiscuously. Apprehending a famine for the agriculturists, they sent into Etruria, and the Pomptine district, and to Cumae, and at last to Sicily also to procure corn."
-Livy, History of Rome, IV 25.3 "a quiet in other matters" could be less subtly stated as "all other business came to a halt due to the disease".
Apollo standing beside Hygieia with scientific instruments scattered on the ground; Society of Parisian Surgeons. (Etching AD 1731); British Museum Collection# 1987,0620.35.
This coin from Trebonianus Gallus features Apollo Salutaris, and was most likely issued as a call to the god to preserve the Roman people from a plague. There was a plague called the Cyprian Plague in Rome between AD 249 and 262 and this coin was issued circa 253.
The plague is called today the Cyprian Plague after St. Cyprian, who wrote about this plague in "De Mortalitate" and described the symptoms:
That now the bowels loosened into a flux exhaust the strength of the body, that a fever contracted in the very marrow of the bones breaks out into ulcers of the throat, that the intestines are shaken by continual vomiting, that the blood-shot eyes burn, that the feet of some or certain parts of their members are cut away by the infection of diseased putrefaction, that, by a weakness developing through the losses and injuries of the body, either the gait is enfeebled, or the hearing impaired, or the sight blinded, all this contributes to the proof of faith.'
- St. Cyprian, On Mortality, Ch. 14 The Plague of Cyprian may have been caused by a filovirus - the family of RNA viruses that includes Ebola.
Roman Imperial, Trebonianus Gallus, AD 251-253, AR antoninianus, Rome, AD 253 Obv: IMP CAE C VIB TREB GALLVS AVG, radiate, draped and cuirassed bust of Trebonianus Gallus right Rev: A-POLL SALVTARI, Apollo Salutaris standing facing, head left, holding olive branch and lyre resting upon rock Ref: RIC 32; RSC 20
Here is a Sestertius of in the name of his son Volusianus.
Volusian, Æ Sestertius
Obv: IMP CAE C VIB VOLVSIANO AVG, bust of Volusian, laureate, draped, cuirassed, right
Rev: CONCORDIA AVGG, Concordia, draped, standing left, holding patera in right hand and double cornucopiae in left hand, S C
Ref: RIC 249
Volusian was Caesar from July-November 251 and became emperor from from November 251 to August 253. Gallus raised him up to Augustus after Hostilianus (Decius' son whom Gallus had raised to Augustus) died of the plague. (see: De Imperatoribus Romanis).
This coin was attributed to Volusian by British Museum cataloger G. F. Hill, however the bungled legends were better linked with Valerian by Barbara Levick in 1966. This mint clearly had quite a few illiterate die makers. Aemilianus, commander of the Moesian troops, defeated Trebonnianus and became emperor for 3 months before he was killed by his own troops after Valerian, governor of the Rhine provinces, declared himself emperor.
Pisidia, Antiochia, Valerian I. AD 253-260. Æ (22mm, 4.58g).
Obv: IMP CAERAS LL OVALERIC (sic) Radiate, draped, and cuirassed bust right, seen from behind
Rev: ANTIO - HIOCIA, vexillum surmounted by eagle between signa, each surmounted by wreath; S R across field.
Notes: these coins were struck by town on the route to and from the eastern frontier. The SR credibly linked in Senatus Romano (abbreviating SPQR)
A statue by Timarchides of Athens featuring Apollo with a lyre is referenced by Pliny. This statue in the Vatican Museum is a 2nd century Roman statue of Apollo Citharoedus.
2006. Photo: Sergey Sosnovskiy (CC BY-SA 4.0)
There is a statue of Apollo of Cyrene in the British museum that is thought to have been modeled on a statue by Timarchides of Apollo Citharoedus.
The enduring connection between Apollo and health is illustrated with the 1731 illustration of Apollo and Hygeia used by the Société académique de chirurgie de Paris. The same image can be found on this medal at the Louvre.
A more modern example in a group researching Alzheimer's disease named Apollo Health.
References (others referenced inline above)
British Museum Collection, Item Number 1987,0620.35.
Hill, P. V. (1962). The Temples and Statues of Apollo in Rome. The Numismatic Chronicle and Journal of the Royal Numismatic Society, 2, 125–142.
Apollo - Fritz Graf (2009)
Solving the Mystery of an Ancient Roman Plague, Kyle Harper, The Atlantic, Nov 1 2017 (retrieved 3-Oct-2021)
Statue of Apollo Citharoedus. Rome, Vatican Museums, Pius-Clementine Museum, Room of the Muses, 16.
WorldHistory.org, Plague of Cyprian, 250-270 CE
Moral Panic and pandemics, www.thelancet.com, Vol 375, 29-May-2010.