I was up at the MN Honey producer summer meeting. One of the speakers was Meghan Milbrath. She is an epidemiologist.
Epidemiologists
are public health professionals who investigate patterns and causes of
disease and injury in humans. They seek to reduce the risk and
occurrence of negative health outcomes through research, community
education, and health policy. They get involved with mass outbreaks of disease and epidemics.
Meghan describes the current Varroa issue as an epidemic. Here is a link to her site for Planning for Varroa.
https://pollinators.msu.edu/resources/beekeepers/planning-for-varroa/