Some pathogens, such as HIV, can be transmitted both vertically and horizontally. How do you expect virulence of such pathogens to compare with that of pathogens that are transmitted?

Some pathogens are transmitted by a single route and others by several, the more transmission routes are recorded, the more pathogens they are, in the HIV virus the transmission is vertical and horizontal therefore it has high pathogenicity, on the other hand, the varicella virus is transmitted only by inhalation.

Explanation:

The vertical route is the transmission through childbirth, it is the moment in which the mother contacts the child's blood and transmits the virus, nowadays the vertical contagion of HIV is highly controlled.

On the other hand, the horizontal route is also called parenteral, it is one that consists of the inoculation of the virus through uncontrolled blood transfusions, intravenous drug addiction by syringe compartment, or uncontrolled injections.