The aerosolized dust created by vacuums contain bacteria and mold that "could lead to adverse effects in allergic people, infants, and people with compromised immunity," according to researchers at the University of Queensland, Australia and Laval University, Quebec, Canada.
Vacuum dust: A previously unknown disease vector (Phys.org News)
Popular Press (Daily Mail UK)
Obviously just walking over a floor that needs cleaning will also raise dust into the air containing the same bacteria and mold. However, it does make you think about the possible benefits of changing flooring or your floor cleaning method if there are susceptible people in your household. Might also be wise to steer clear of cleaning appliances in public places too.