• Source: A review is needed of wastewater testing to work out its effectiveness in picking up Covid-19 outbreaks, epidemiologist professor Michael Baker says. Wastewater testing at ESR (file photo). Source: 1 NEWS The weak positive results from Wellington sampling, announced over the weekend, showed it was good at detecting virus fragments, but its role in discovering active outbreaks early is still unclear, he told RNZ's Morning Report. ESR reported on Friday there had been a weak positive test result from a sample taken in Wellington. A follow-up sample on Saturday returned a second weak positive result. The two weak positive results are most likely due to recently recovered cases continuing to shed the virus, the Ministry of Health said.