Does the new CDC guidance about avoiding 15 minutes cumulative contact mean with masks or without masks?

Infection and Spread Masks Testing and Contact Tracing

A: In the community setting, someone who meets the criteria for being a close contact to a case of COVID-19, meets the criteria REGARDLESS of whether or not they or the case had on a mask.

Why is someone considered a close contact regardless of whether they had on a mask?

While cloth masks are most definitely recommended for use by CDC (see here for more info), they state that they do not currently recommend close contacts be differentiated by whether someone was wearing a fabric face covering or other personal protective equipment (PPE) because “the general public has not received training on proper selection or use of respiratory PPE” (see more info here). In other words, there is too much variability in the type of masks worn and whether they are worn correctly and consistently by the general public for mask use to be considered in determining if someone meets the criteria of being a close contact to a case.

Beyond that, masks are to be used as an additional layer of protection on top of maintaining at least 6 ft distance from others and not as a substitute for social distancing. This DOESN’T MEAN masks don’t help reduce transmission of COVID-19! Keep wearing cloth face masks in conjunction with taking other measures to reduce transmission of COVID-19!

In what way did the criteria for being a close contact change exactly?

Previously, the criteria for being a close contact (i.e., exposed) to someone with COVID-19, was spending>15 minutes within < 6ft of someone diagnosed with COVID-19 starting 2 days before symptoms onset or a positive test result (if case had not developed symptoms) and until the person met the criteria to end their isolation period (see our prior post on this here).

CDC recently revised these criteria, however, such that a close contact is NOW defined as being < 6ft of someone diagnosed with COVID-19 for a *cumulative* period of > 15 minutes *over a 24-hour period*. In other words, the criteria are now more explicit in denoting that the 15 minutes of being < 6ft from a case can occur over several shorter periods (i.e., doesn’t have to occur all at once) and can occur over a longer span of time (i.e., a whole day) and still be relevant for transmission.

Why did the criteria change anyway?

This change in the criteria was announced the same day that a CDC case report was released in which a correctional officer who wore a cloth mask, gown and eye protection had 22 brief encounters, within < 6 ft of 6 individuals with COVID-19 who were awaiting their test results and wore masks most but not all the time, for a total of 17 minutes of time over an 8 hour period. The correctional officer then became positive for COVID-19 with no other known contacts to a case (see here for more info). Thus, this individual was infected with COVID-19, after repeated instances of being < 6ft apart from the cases, for periods of < 15 minutes at a time, over an extended period across a day.

This change also coincides with the broader recognition by CDC and others that while being < 6ft apart from a case of COVID-19 for > 15 minutes has been used as an operational definition for contact tracing investigations, it is not a magic cut-off for transmission to take place and other factors should be taken into consideration as well (see more info here). Indeed, CDC also now acknowledges that factors such as how close individuals were to each other, the duration of time they spent in close contact, whether the individuals had symptoms, whether individuals were likely to be producing aerosols (such as via coughing, singing, or shouting), and the level of ventilation (indoors vs. outdoors) and crowding are also relevant in defining a close contact (see here for more info).
So what does this mean in practical terms?

The big take-away here is that we shouldn’t assume that just because we spend time < 6ft from someone for less than 15 minutes at a time, that this is sufficient to prevent transmission of COVID-19 if repeated exposures happen over a 24-hour period. Moreover, we need to keep in mind the range of other factors listed above when trying to reduce our risk of COVID-19.

All the more reason to apply AS MANY of the #SMART criteria (Space-6ft, Mask-wear one, Air-keep it fresh, Restrict-keep it small, and Time-keep it short) as possible to any social interactions or activities we engage in.

For more background information regarding this change in criteria Stat News Article and Medium Article.

Link to original FB post