[MCOH-EH] Testing for measles immunity

[Tim Crump]

We follow the CDC document Immunization of Health-Care Personnel (https://www.cdc.gov/mmwr/preview/mmwrhtml/rr6007a1.htm)

"In the event that a HCP who has 2 documented doses of MMR vaccine is tested serologically and determined to have negative or equivocal measles titer results, it is not recommended that the person receive an additional dose of MMR vaccine. Such persons should be considered to have presumptive evidence of measles immunity. Documented age-appropriate vaccination supersedes the results of subsequent serologic testing. Because rapid vaccination is necessary to halt disease transmission, during outbreaks of measles, serologic screening before vaccination is not recommended"


Tim Crump, MSN, FNP
Tim Crump, MSN, FNP
He/Him/They/Them
Family Nurse Practitioner
Multnomah Pavilion (Second Floor, SW Wing), 3161 SW Pavilion Loop
Occupational Health
Healthcare Human Resources

+ ASIST Trained Caregiver<https://www.ohsu.edu/education/suicide-prevention>

Oregon Health & Science University
Occupational Health
3181 SW Sam Jackson Park Rd,
Mail code: UHN 89
Portland, OR 97239-3098
Department Phone: 503-494-5271
Office Phone: 503-494-5184
Fax: 503-494-4457
Email: crumpt at ohsu.edu<mailto:crumpt at ohsu.edu>

Wed-Fri, 7:30-6:00

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From: MCOH-EH <mcoh-eh-bounces at mylist.net> On Behalf Of Galaid, Edward via MCOH-EH
Sent: Friday, August 1, 2025 8:20 AM
To: mcoh-eh at mylist.net
Cc: Galaid, Edward <Edward.Galaid at rsfh.com>
Subject: [EXTERNAL] [MCOH-EH] Testing for measles immunity

A Charleston hospital  had a suspected case of measles in their ED.  One of the HCWs who had direct contact with kid,  was fully vaccinated was found to have an indeterminate IgG result (by report).
She received a dose of vaccine and it's anticipated that she will be excluded from work from day 5-21 per the CDC guidance.

 I've started reading about waning immunity to MMR among those who received their primary series of vaccine, and also about the performance of the measles-specific IgG immunoassays.  Check out:  Latner et al Qualitative Variation among Commercial Immunoassays for Detection of Measles-Specific IgG J Clin Microbiol . 2020 May 26;58(6):e00265-20.   This study reports an 11% false negative rate.

In fully vaccinated adults with negative IgGs, is it valid to retest with a different kit?    The authors concluding statement " Individuals that have negative or equivocal results for measles IgG should be vaccinated or revaccinated (6<https://urldefense.com/v3/__https:/pmc.ncbi.nlm.nih.gov/articles/PMC7269388/*B6__;Iw!!Mi0JBg!IQvcfMEUjTbECg4zHgZOL7TvlZRKcvJnZMn1xBQsKexkhztjEG91EIPVj4uqjZd7qLqmKeA49C24J091$>). In some cases, vaccination is not possible and testing with a second line diagnostic assay may be necessary to determine immune status."

Oh, and by the way, if we exclude someone from work, waiting to see if they blossom forth with a rash... how are we going to deal with missed wages?

Ed Galaid


Edward I. Galaid, MD, MPH, FACOEM
ABIM, ABPM (OM)
Medical Director, Occupational Medicine
Roper St. Francis Healthcare, Charleston SC
Chair, Public Safety Medicine Section, American College of Occupational and Environmental Medicine
NFPA 1580 Technical Committee on Emergency Responders Occupational Health
5070 International Blvd Ste. 131  North Charleston, SC 29418
843-402-5053 (O)




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