Methods: HCWs who had previously been vaccinated with VZ vaccine then had VZ ELFA, VZ ACIF, and VZ CMI testing all done on the same blood specimen. VZ ELFA was performed by Focus Technologies (Cypress, CA) and VZ ACIF by bioMérieux Vitek, Inc. (Hazelwood, MO). CMI response was measured by lymphocyte transformation assay. Positive and negative results are determined by comparison to internal controls. HCWs completed a survey relating to prior VZ exposures.
Results: In 2014 10 HCWs were identified according to the parameters above. Male = 5; Female = 5. Mean age = 42.5 years; Median = 42 years; Range = 24-63.
|VZ ELFA||Neg||Neg||Neg||Neg||Neg||Neg||Neg||Equiv||Equiv||Neg||2 E/8 N|
|VZ ACIF||Neg||Neg||Neg||Pos||Pos||Neg||Neg||Neg||Pos||Neg||3 P/7 N|
|VZ CMI||Neg||Pos||Pos||Pos||Pos||Pos||Pos||Pos||Pos||Pos||9 P/1 N|
Survey results revealed that only one HCW was born and raised in the tropics (Jamaica). Eight of 10 grew up with siblings, 4 of whom had varicella. Four of 10 have children of their own – none have had varicella. Six of 10 have been repeatedly exposed to patients with varicella and/or shingles – none developed clinical varicella.
Conclusion: In this small selective sample of previously vaccinated HCWs, serological evidence of immunity to VZ by the ELFA method remained difficult to demonstrate while VZ CMI responsiveness was present in 9 of 10 tested suggesting that they have recall to the VZ antigen. Exactly what that means in terms of protective immunity remains unclear. We will follow up and track the future clinical, serological, and CMI responses of these HCWs to exposures to VZ to more precisely define the role of CMI responsiveness .
A. E. Brown,
Y. W. Tang, None
S. Low, None
P. Maslak, None
K. Smith, None
L. Gomez, None