The SARS-CoV-2 transmission riddle - Part 14 close contact

Of transmission and censorship

This was probably the most challenging riddle to write so far. The reason is simple: everyone knows what close contact means, but there are no universal definitions.

Is it a mode of transmission, or is closeness a variable? Does it involve touching someone, or can it include airborne particles emitted from a short distance? If so, what distance: 1, 2, 3 metres or more? And what particles do we include, droplets, aerosols, or fomites agitated by someone close to you?

You expect the international literature to be clear on these points and have universally accepted definitions. Not so.

When we reviewed international literature apart from the now well-known evidence quality problems, we came up against the problem of precisely what is meant by close contact. For example, the US CDC defines it as:

Close contact: Someone who was within 6 feet of an infected person for a cumulative total of 15 minutes or more over a 24-hour period starting from 2 days before illness onset (or, for asymptomatic p…