The Justinian plague of 562 A.D.. An Electromagnetic drama?

In the pre Christian era Claude Schaeffer documents a series of great geophysical other catastrophic events that devastated the human race! But what about other decimating but lesser dramas that reached into the present era? The virulent Justinian plagues of around 50 A.D was just such a drama. But what caused it. Mythology and much early documentation lays the blame at the foot of cometry excursions! Is there justification in this claim?