Covid-19
13 The sixth angel sounded his trumpet, and I heard a voice coming from the four horns of the golden altar that is before God. 14 It said to the sixth angel who had the trumpet, “Release the four angels who are bound at the great river Euphrates.” 15 And the four angels who had been kept ready for this very hour and day and month and year were released to kill mankind for the third time. 16 The number of the mounted troops was twice ten thousand times ten thousand. I heard their number.
17 The horses and riders I saw in my vision looked like this: Their breastplates were fiery red, dark blue, and yellow as sulfur. The heads of the horses resembled the heads of lions, and out of their mouths came fire, smoke and sulfur. 18 For the third time mankind was killed by the three plagues of fire, smoke and sulfur that came out of their mouths. 19 The power of the horses was in their mouths and in their tails; for their tails were like snakes, having heads with which they inflict injury.
Revelation 9:13-19
The Fifth Trumpet brought us to September 2019. The Sixth Trumpet starts directly after the Fifth Trumpet. Interestingly enough, September 2019 is the month during which experts now believe that the Covid-19 pandemic started:
https://www.thesun.co.uk/news/13206255/covid-plagued-eu-september-2019-italy/
We are told that this is the third time that these four angels have attacked mankind. It seems that the four angels control the cavalry. Can we conclude that the cavalry that is described is actually a description of the sub microscopic infectious agents which are viruses?
The cavalry spoken of release three plagues of judgement onto the earth, symbolized by the fire, smoke and sulphur.