Dozens of the over 700 unaccompanied minors who crossed the U.S.-Mexico border illegally and were transported to a shelter at a San Diego convention center have tested positive for COVID-19, according to local and health officials cited in multiple media reports. U.S. Health and Human Services spokesperson Bonnie Preston told NBC7 San Diego on Monday that at least 69 minors—teenage girls between 13 and 17—had tested positive and were all asymptomatic. Preston told the outlet that there were now 723 girls being housed at the San Diego Convention Center—whose exhibit halls have been transformed into a temporary shelter—with around 250 more expected to arrive every other day until capacity is reached of 1,450. Separately, San Diego County Supervisor Nora Vargas confirmed to News 8 that there were positive cases of COVID-19 among the unaccompanied children at the convention center. The outlet reported that none of the cases were serious enough for the children …