No, but viral infections spread most effectively from human to human, and Native Americans (with some exceptions) did not form large cities.

Stuff like STDs probably existed, for instance, and those are viral infections for the most part, but STDs do not spread nearly as well as something like smallpox does.

The big difference here is that smallpox can be transmitted through airbourne droplets from coughing or sneezing, or through physical contact. I am not saying it was intentional by the Europeans (I couldn’t find much evidence for the smallpox blankets existing), but it was very effective in eradicating the Native American population.