Wastewater concentrations of COVID-19 in Maine’s most populous counties continued to increase last week, suggesting the virus is not letting up with hospitalizations surging. The latest reports are concerning because wastewater is considered a leading indicator of cases. An uptick beginning in April preceded the hospitalization surge. The rise of concentrations in Maine’s large population centers suggests the virus situation could worsen. Wastewater in York, Cumberland and Androscoggin counties show levels of COVID-19 at the highest they have been since early February, according to monitoring by the Maine Center for Disease Control and Prevention and Biobot.