From Dr. Stuart Weiss

Dr. Stuart Weiss, FACEP, FAAP, CBCP

October 21, 2020

Prolonged viral shedding, Definition of Close Contact Changed today

Prolonged Viral Shedding

A client of mine asked me to comment on an employee that keeps testing positive. Should they be allowed to work.

I thought it might be a good time to review the current thinking on this topic. In an article that I just saw today in the journal Infection Control and Hospital Epidemiology, they took a look at 77 different studies in the medical literature that looked at CoViD-19 infections. All studies looked at patients using PCR based testing. The average duration of viral RNA shedding was 18.4 days with a maximum of 92 days. In this compilation of studies, live virus was detected from 6 days prior to onset up until 20 days after symptom onset.

Based on similar studies, the CDC issued guidance on Sept 20th advising that people can be cleared after ten days if they have no symptoms. The guidance is here: https://www.cdc.gov/coronavirus/2019-ncov/if-you-are-sick/end-home-isolation.html

If you have symptoms, you are cleared after ten days and fever free for 24 hours and symptoms improving.

So whether you follow the CDC and allow return to work at ten days or the new study's finding of 20 days, you may still have employees that shed viral particles for weeks and continue to test positive long after they are no longer infectious.

However, if after 4 months, an employee tests positive again, they are one of those unlucky folks who got reinfected and the quarantine clock starts over again.

Definition of Close Contact changed

For quite some time, the CDC has defined Close Contact as closer than 6 feet for more than 15 minutes. Today, after reviewing a case of a prison guard who was in contact with a group of infected prisoners for multiple short periods of time and became infected, the guidance was changed.

Close contact is now defined as being within 6 feet of an infected person for a cumulative total of 15 minutes within a 24 hour period. So even shorter exposures add up. This points to the fact that corona virus may spread easier than originally thought. This change may have important impacts on the way contact tracing is done.

Be well,

Dr. Stu Weiss

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