Conversion differs slightly for each virus. I got this from something published (or presented, can’t recall) by Mark Holodniy, MD, FACP, CIC, Professor of Medicine, Stanford University School of Medicine and Palo Alto VA. Viral load results may be expressed in copies/ml or genome equivalents (GE)/ml rather than international units (IU.) But, IU conversion factors are:

For HIV, 1 IU = 1.74 copies.

For HBV, 1 IU = 5.6 copies.

For HCV, 1 IU = 3.8 copies.

Following are recommended viral loads for infected HCW performing invasive procedures under SHEA guidelines compared to CDC:

SHEA recommendations:

Clinical Activities	Recommendation	Permissible Viral Load
“Category 1 or 2” de minimis, or theoretical but unlikely risk	No practice restriction Receive follow-up by personal physician Adhere to optimal infection control procedures Double glove for Category 2 procedures	N/A
“Category 3” Definite Risk Procedure	Viral load check twice yearly Restricted from high risk procedures if viral load above permissible level Receive follow-up by personal physician Adhere to optimal infection control procedures Double glove for high risk procedures	HBV <10,000 GE/mL (about 2000 IU/ml) HCV <10,000 GE/mL (about 2500 IU/ml) HIV <500 GE/mL (about 300 IU/ml)

CDC Recommendations (Hepatitis B only)

Clinical Activities	Recommendation	Permissible Viral Load
“Category 2” Low or No Risk Procedure	No panel oversight needed Receive follow-up by personal physician	N/A
“Category 1” Definite Risk Procedure	Viral load check twice yearly Restricted from high risk procedures if viral load above permissible level Receive follow-up by personal physician Adhere to optimal infection control procedures	HBV < 5,000 GE/mL (about 1,000 IU/ml)

Hope this helps,

Melanie

From: MCOH-EH [mailto:mcoh-eh-bounces@mylist.net] On Behalf Of Galaid Edward I
Sent: Tuesday, November 12, 2019 10:19 AM
To: mcoh-eh@mylist.net; Occ-Env-Med-L@listserv.unc.edu
Subject: [EXTERNAL] [MCOH-EH] Genome Equivalents as a measure of viral load

This is pertaining to the unit of measure that is used in the SHEA HCP with HBV/HCV/HIV infection document (https://www.shea-online.org/images/guidelines/BBPathogen_GL.pdf) to quantify viral load.

My Lab Director and his colleagues have not been able to come up with a conversion factor to express viral load as copies/mL or IU’s.

Appreciate any info on how you’re handling this.   This is not a new issue.  I am just stumped.

And maybe the SHEA document from 2010 is due for an update.

Thanks

Ed Galaid

Edward I. Galaid, MD, MPH, FACOEM

ABIM, ABPM (OM)

Medical Director, Roper St. Francis Physician Partners Occupational Medicine

Charleston, SC

Member, ACOEM Task Group,  Guidance for the Medical Evaluation of Law Enforcement Officers

(O) 843-402-5053

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