When testing for monkeypox virus, only swab samples taken directly from a lesion (rash or growth) should be used, according to the Food and Drug Administration (FDA).

In a recent safety communication, the Agency warned that use of an alternate sample type (eg, blood, saliva) may lead to false test results and is not supported by clinical data. Guidance from the Centers for Disease and Prevention (CDC) states that the recommended specimen type is skin lesion material.

For patients who were tested for monkeypox using a different method, the FDA suggests retesting using the lesion swab method if an inaccurate result is suspected. The FDA-cleared CDC non-variola orthopoxvirus test can detect monkeypox from a lesion sample. The Agency is currently working to increase production and distribution of the test and has cleared additional reagents and automation to expand testing capacity.

Though laboratory developed tests (LTDs) may be available for monkeypox, these tests, which are designed, manufactured and used within a single laboratory, may not have been reviewed by the FDA. As with other LTDs, the Agency has generally not enforced premarket review and other regulatory requirements for these devices. At this time, the FDA does not plan to deviate from its current policy with respect monkeypox LTDs.    

The latest information about the 2022 monkeypox outbreak in the US can be found here.

Reference

The US Food and Drug Administration. For monkeypox testing, use lesion swab samples to avoid false results: FDA safety communication. July 15, 2022. https://www.fda.gov/medical-devices/safety-communications/monkeypox-testing-use-lesion-swab-samples-avoid-false-results-fda-safety-communication