The short answer is the surface stays free of pathogens until the next person touches the surface, so one might assume that a surface must be disinfected after each person uses or touches the surface. Let’s dig a little deeper to answer the above question. The likelihood of disease transmission from a surface can be correlated to the number of pathogens on the surface. For instance, a single pathogenic bacteria on a surface reproduces and grows exponentially to 2.4 million in about 6 hours and continues to multiply at an exponential rate. Neglecting to disinfect these surfaces easily create pathogen levels in the 100’s of billions. It is these neglected surfaces that can transmit disease. This concept is well known in food processing, where killing every single bacterial pathogen on a surface is not possible, it only needs to be brought to a safe level. This is why food contact surfaces are sanitized (killing 99.99% of pathogens). In the case of viral pathogens, it can be minutes to days depending on the pathogens and surrounding conditions. Eventually, without a host, the viral pathogen will die on its own. While a single viral pathogen on a surface could in theory infect someone, it is more likely this occurs when there are 100’s of millions of viral pathogens present.
