Final answer:
Contact precautions break the 'mode of transmission' link in the chain of infection by preventing the transfer of pathogens through touch or contact with contaminated surfaces.
Step-by-step explanation:
In the context of infection control, contact precautions are strategies used to prevent the spread of pathogens by direct or indirect contact. The chain of infection includes several links such as reservoir, mode of transmission, portal of entry, and host. When contact precautions are implemented, the link of the chain that is broken is the mode of transmission. This is due to the interruption of the pathogen's ability to be transferred through touch or contact with contaminated surfaces (fomites). Effective contact precautions reduce exposure by creating barriers, such as using gloves or gowns, to prevent the transmission of infections, thereby protecting both healthcare workers and patients.