Leverage Perspective

The total weights of the atomic bombs employed in WWII were 64kg uranium + 6kg plutonium = 70kg, which killed 226,000 human beings in Hiroshima and Nagasaki. (This figure does not include long-term early deaths from radiation poisoning, which are much more difficult to calculate.)

The total estimated weight of all the Covid-19 virions in the world at any given time is 0.1kg-10kg. Let us use the high end estimate. We know that 10kg of Covid-19 virions has, so far, killed some 4,500,000 human beings worldwide.

This gives us a leverage perspective:

Each kilogram of Covid-199 virus kills 450,000 people at current conditions.
Each kilogram of fissile material killed 3,229 people, in the only example we know ... to date.

Covid-19 is thus approximately 140 times more effective, per weight of material, at killing human beings than are atomic bombs.