The measles vaccine is live and attenuated, meaning post-vaccination, it will replicate itself 15-20 times. These replications are prone to being taken up by particular immune cells in the body, including ones that reside in the intestines. It is not improbable that a sensitive assay would detect this virus’s presence not long after vaccination. Indeed, the assay used by the authors was incredibly sensitive and prone to false positives. The delay between vaccination and the examination of the children was not detailed in the study, and thus may have been different for children on and not on the spectrum. Second, the measles virus was naturally circulating in England at this time, so it is not clear whether the detected virus was from the vaccine or from contagion. Third, the authors did not perform a proper double-blind procedure, aware of who was part of the control and experimental groups, thus making them prone to bias related errors.