Not only the seat but the lid should be down when you flush.

We now know that the "aerosal effect" spreads bacteria far and wide.

Make sure your toothbrush and other personal items are a good distance away from the toilet.

www.pubmed.com

"SIGNIFICANCE AND IMPACT OF THE STUDY: Many individuals may be unaware of the risk of air-borne dissemination of microbes when flushing the toilet and the consequent surface contamination that may spread infection within the household, via direct surface-to-hand-to mouth contact. Some enteric viruses could persist in the air after toilet flushing and infection may be acquired after inhalation and swallowing."

And a paper from Sarah Tam:

"The bacterial mist has also been shown to stay in the air for at least two hours after each flush, thus maximizing its chance to float around and spread (2). "The greatest aerosol dispersal occurs not during the initial moments of the flush, but rather once most of the water has already left the bowl," according to Philip Tierno, MD, director of clinical microbiology and diagnostic immunology at New York University Medical Center and Mt. Sinai Medical Center. He therefore advises leaving immediately after flushing to not have the microscopic, airborne mist land on you (4). Worse still is the possibility of getting these airborne particles in the lungs by inhaling them, from which one could easily contract a cough or cold (6)."

So now I demand that the seat AND the lid are down.