Determination of immunity to vaccinia virus by using diluted inactivated vaccinia vaccine solution for skin testing.

AIMS: We evaluated the usefulness of skin test prepared by inactivation of vaccinia vaccine in predicting immunity to vaccinia. Skin test was injected to 77 healthy adults. Twenty had a recent smallpox vaccination (group 1). Thirty-seven were long term vacinees (group 2), while 20 subjects had never been vaccinated for smallpox (group 3).

RESULTS

Mean size of induration was 7.9, 5.3 and 0.4 mm for subjects from groups 1, 2 and 3, respectively (P<0.03 for difference between groups). Induration >or=5 mm correlated with neutralizing antibody titer >1:32 (r=0.73, P<0.0001).

CONCLUSIONS

The skin test is a potentially useful tool for the assessment of immunity to vaccinia.