The OPV AIDS hypothesis has, however, been rejected within much of the medical community and is contradicted by at least one article in the journal Nature, which claims the HIV-1 group M virus originated in Africa 30 years before the OPV trials were conducted.[1] However, the field work within the study was limited to just 34 samples all taken within the immediate vicinity of Kisangani. Despite this the journal Science refuted Hooper's claims, writing: "[I]t can be stated with almost complete certainty that the large polio vaccine trial... was not the origin of AIDS."[18]