Cell-towers are dependent on electric power from the grid, but many of them have backup batteries, and in some cases generators that can power the antennas independently for longer.
The probability of actually catching the flu or a bacterial infection as a result of cell phone contact is actually dependent on a number of factors how long the viruses or bacteria have been on the phone surface.
And the essential deployment of new cell towers, antennae, and other infrastructure remains dependent on notoriously unresponsive local zoning authorities.