Frequency of vaccinia virus isolation on semipermeable versus nonocclusive dressings covering smallpox vaccination sites in hospital personnel.
BACKGROUND
The Centers for Disease Control and Prevention recommends a semipermeable occlusive dressing for hospital workers who receive smallpox vaccination.


OBJECTIVE
The study was designed to determine the frequency of vaccinia virus isolation from the outer surface of semipermeable dressings and to compare the prevalence of vaccinia virus on the outer surface of semipermeable dressings with its prevalence on the outer surface of nonocclusive dressings.


METHODS
A prospective, observational study was conducted on hospital employees who received smallpox vaccination at a military academic medical center. Subjects were instructed to wear a semipermeable dressing if they had direct patient contact. Employees without direct patient care had the option of wearing a semipermeable dressing or a nonocclusive dressing. Prior to a programmed dressing change, the outer surface of the bandage site was swabbed and cultured for virus. Samples were considered positive when cytopathic effects were observed, with results confirmed as vaccinia by polymerase chain reaction.


RESULTS
A total of 212 cultures were obtained from 93 subjects. All cultures directly obtained from active lesions were positive (13/13). Positive cultures were obtained from 7% (10/135) of the semipermeable dressings and 23% (15/64) of the nonocclusive dressings (P <.05). Ten percent (8/79) of the semipermeable dressings with purulent exudate observed underneath the bandage were culture positive, compared with 4% (2/56) of semipermeable dressings with no purulent exudate observed underneath the bandage (P=.19).


CONCLUSIONS
Compared with nonocclusive dressings, the semipermeable dressing reduced, but did not eliminate, the frequency with which vaccinia virus was cultured from the surface of the dressing. Virus was present, but only rarely, on the dressing surface in the absence of purulent exudate under the semipermeable dressings.
Hepburn
Matthew J
MJ
Department of Medicine, Brooke Army Medical Center, and US Army Medical Research Institute of Infectious Diseases, MCMR-UIM-O (Hepburn), 1425 Porter Street, Ft. Detrick, MD 21702-5011, USA.
Dooley
David P
DP
Murray
Clinton K
CK
Hospenthal
Duane R
DR
Hill
Bonnie L
BL
Nauschuetz
William N
WN
Davis
Kepler A
KA
Crouch
Helen K
HK
McAllister
C Kenneth
CK
D001458:Bandages; D006772:Hospitals, Military; D006801:Humans; D017053:Infection Control / Q000379:methods*; D009779:Occlusive Dressings / Q000821:virology*; D009784:Occupational Diseases / Q000453:epidemiology / Q000517:prevention & control; D010564:Personnel, Hospital; D017410:Practice Guidelines as Topic; D015995:Prevalence; D011446:Prospective Studies; D012899:Smallpox / Q000517:prevention & control; D012900:Smallpox Vaccine / Q000008:administration & dosage / Q000009:adverse effects*; D013781:Texas / Q000453:epidemiology; D014615:Vaccinia / Q000453:epidemiology / Q000517:prevention & control / Q000635:transmission*; D014616:Vaccinia virus / Q000302:isolation & purification*
D012900:Smallpox Vaccine