Indirect contact transmission studies.

You can’t truly get a hospital room clean.
 
An estimated 722,000 patients get an infection while being treated in US acute care hospitals. 75,000 with those conditions die. The study looked at 20 studies published between 1998 and 2014. It found that, even after cleaning, the most common pathogens found in hospitals were MRSA, VRE and C. difficile on bed rails, tray tables, call buttons, and other hard surfaces.

Reservoirs of MRSA, VRE, Clostridium exist on porous and non-porous surfaces in hospital rooms.
 
Eighty studies were evaluated. HAIs are a leading cause of illness and death us US and worldwide. Porous (curtains) and non-porous hard surfaces (bed rails) were included in studies. “Contaminated surfaces are a reservoir for transmission of pathogens directly through patient contact with the environment or indirectly through contamination of healthcare workers’ hands and gloves.”

“There is now growing evidence that contaminated fomites or surfaces play a key role in the spread of viral infections”...”

“...viruses are shed in large numbers in body secretions, including blood, feces, urine, saliva, and nasal fluid (10, 33, 34, 39, 48, 58)...If viruses remain viable on surfaces long enough to come in contact with a host, the virus may only need to be present in small numbers to infect the host (10, 58, 66, 71). After contact with the host is achieved, viruses can gain entry into the host systems through portals of entry or contact with the mouth, nasopharynx, and eyes…current scientific evidence also suggests that fomites are an important vehicle in the spread of respiratory viruses…A majority of respiratory viruses are enveloped (parainfluenza virus, influenza virus, RSV, and coronavirus) and survive on surfaces from hours to days.”

Influenza and Coronavirus can be spread via shedding onto environmental surfaces and hands and cause people to self-innoculate noses. If hands can spread viruses into the nose, can nasal cannula prongs do so as well?
 
“Once contaminated from the environment, hands can then initiate self-inoculation of mucous membranes of the nose, eyes or mouth. Mathematical and animal models, and intervention studies suggest that contact transmission is the most important route in some scenarios.”

MERS can be spread through surfaces such as bedsheets, bedrails, IV fluid hangers, and X-ray devices up to 5 days after the last positive detection in respiratory specimens aka after the patients are recovered.
 
“Many environmental surfaces of MERS patient rooms, including points frequently touched by patients or healthcare workers, were contaminated by MERS-CoV. Viral RNA was detected up to five days from environmental surfaces following the last positive PCR from patients' respiratory specimens… In addition, MERS-CoV was isolated from environmental objects such as bed sheets, bedrails, IV fluid hangers, and X-ray devices. During the late clinical phase of MERS, viable virus could be isolated in 3 of the 4 enrolled patients on day 18 to day 25 after symptom onset.”

How disease is spread via respiratory droplets (skip to the results section).

In a MERS study, 16 fomites (ie, stethoscopes, bag valve masks, blood pressure cuffs, nasal prongs, pillows, and keyboards) were swabbed and 13 tested positive for MERS-CoV.