Drug Interactions between trichophyton skin test and typhoid vaccine, live

ADJUST DOSING INTERVAL: Reactivity to diagnostic skin test antigens may be temporarily depressed in patients who have recently been vaccinated with live, attenuated viral or bacterial vaccines, potentially resulting in a false negative reaction. The mechanism of this interaction is not well described, but may involve live vaccine-mediated suppression of the immune system, possibly via inhibition of the lymphocyte mitotic response. Clinical data are limited. In one study, 26 tuberculin-positive children were vaccinated with the live, attenuated mumps virus vaccine. A tuberculin skin test was administered on day 1 and then every 7 days for 4 doses, with the magnitude of induration measured 48 hours after each skin test. The mumps vaccination was given on day 3 of the study. A significant decrease in the tuberculin reaction was observed in 17 of the 26 children. Delayed hypersensitivity to the tuberculoprotein virtually disappeared within 2 weeks of the live, attenuated mumps vaccine for many of these children and for some the depression of delayed hypersensitivity persisted through the 4-week observational period. A similar response was also reported in a separate study of 15 children with tuberculosis who developed mild cases of measles following vaccination with the live measles vaccine, with or without gamma globulin. The tuberculin skin test was documented as negative often during the measles incubation period and frequently observed to be negative during the first week of measles symptoms in these children. While this reaction has only been reported clinically in patients receiving the tuberculin skin test with certain live, attenuated viral vaccines, it may also apply to other skin tests and live, attenuated bacterial vaccines as well.

MANAGEMENT: Clinicians should be aware of the potential for falsely insignificant or false-negative results when performing delayed-hypersensitivity skin testing on patients who have recently received live, attenuated viral or bacterial vaccines. In general, tuberculin skin tests can be administered before a live vaccine, given simultaneously with the live vaccine at separate sites (preferred option), or the tuberculin skin test should be postponed for at least 4 weeks after immunization. For the live, non-replicating smallpox and monkeypox vaccine, some authorities recommend following the same guidelines that are recommended for other live vaccines with the tuberculin skin test; however, if a delay in the tuberculin skin test would cause a substantial burden for the patient, they state that any sequence of vaccination and tuberculin skin test is acceptable. Although not addressed in the labeling for other diagnostic skin tests, these recommendations should be considered when evaluating skin testing and administration of live vaccines. Local vaccination guidelines and prescribing information for both the vaccine(s) and individual skin test(s) should be consulted for further guidance.