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The recommendations to avoid close contact with other humans and to wear facial coverings when close contact is unavoidable are influenced from studies investigating the spread of the SARS-CoV-2 virus and other respiratory pathogens1,2,3,4, studies of the transmission of respiratory droplets and aerosols
5,6,7, the protective effects of facial coverings
8,9,10, and the eye protection (i.e., goggles or disposable face shield that covers the front and sides of the face)
15 as well as practical considerations. Furthermore, the discovery of the importance of
asymptomatic and
pre-symptomatic spread of the SARS-CoV-2 virus adds additional support for these behavioral modifications, with the CDC recently estimating that up to 35% of those infected will remain asymptomatic throughout the course of their illness.
Per CDC guidance, Close Contact is defined as:
- being within approximately 6 feet (2 meters) of a person with COVID-19 for a prolonged period of time, or
- having direct contact with infectious secretions of a person with COVID-19 such as being coughed on.
The currently available data are insufficiently robust to precisely define a duration of time that constitutes a “prolonged” exposure in all situations. However 15 minutes is a reasonable duration to use for a rule of thumb. Previous guidance from the CDC utilized 10 minutes of close exposure in non-healthcare settings, and “a few” minutes in healthcare settings; newer
recommendations for post exposure evaluation in travel, community, and healthcare settings have been aligned to provide consistency. Shorter contact times are still reasonable in healthcare settings when patients are highly symptomatic, coughing, or when aerosol-generating procedures are performed.
Once close contact has been confirmed, the recommendations for management of the exposed individual depends upon other factors, such as whether the infected individual exhibited symptoms, whether the infected individual was wearing a facemask, the PPE worn by the exposed worker, and whether the worker is considered essential.
Guidance for Healthcare related exposures:
Guidance for risk assessment and work restrictions for healthcare personnel (HCP) was last updated on May 23, 2020 and provides a simplified approach based on identifying HCP who should be excluded from work following exposure.12 Exposed HCP who wore a facemask and
eye protection, who wore all PPE (gown, gloves, eye protection and respirator) during an aerosol-generating procedure, would not require
post exposure work restrictions under this guidance. In addition, HCP who wore a mask or respirator in contact with a patient who was wearing a facemask or a cloth face covering would not need to be excluded from work.
Outside the healthcare setting, PPE is currently less readily available and of less certain quality, and workplace characteristics are arguably more variable, thus creating additional challenges. The CDC in defining a Close Contact does not take into account whether the individuals involved were wearing a non-respirator facial covering. On the other hand, usage of non-respirator facial coverings will impact the outcomes of the risk analysis when determining the appropriate recommendations for quarantine of the exposed persons. Guidance for community-related exposures
13 and travel-related exposures
14 has also been provided by the CDC. Nevertheless, the variable nature of the workplace supports an individual risk assessment for each employer based on their unique characteristics.
Guidance for Non-Healthcare related exposures:
When a close contact occurs in a non-healthcare workplace, the employer's risk assessment should consider at a minimum the following: type/quality/compliance of face covering (if any) used, any additional PPE used, and the site environmental conditions (i.e. temperature, humidity, airflow, etc.). Furthermore, it is advisable to gather a list of all contacts (close contacts and otherwise) when a non-healthcare workplace exposure or presumed exposure to COVID-19 occurs. In doing so, should transmission of the SARS-CoV-2 occur in the non-healthcare workplace, a
root cause analysis could be undertaken to determine if the unique characteristics of the respective workplace requires additional precautions in the future over and above those of the CDC.
Defining a Close Contact and determining the appropriate actions to take should a Close Contact occur highlight some of the uncertainty surrounding the SARS-CoV-2 virus and COVID-19. As future information becomes available, actions both in the healthcare and non-healthcare employment settings will require modification.