The COVID-19 delta variant is spreading rapidly worldwide and public health state officials are turning again to wastewater for answers.
The delta variant, which first emerged in India last fall, accounted for about 10% of new virus cases in the U.S. by end of June, according to estimates from the Centers for Disease and Prevention, hitting a benchmark of 10K new cases per day.
Although nothing is going to replace the accuracy of an individual PCR test for Covid-19 anytime soon at this particular delta variant the viral load of the waste water can be considered a warning sign for communities where testing is not the case.
Thus, in the initial response with cases still relatively low across a country and with new and emerging variants of the virus a constant concern, the sewage could become a powerful early warning system. After all, each of us produces a sample, more or less every day.
Studies have shown people start excreting the SARS-CoV-2 virus in their human waste up to three days before they develop symptoms of Covid. And while the virus breaks down into harmless genetic fragments once it leaves our body, these can be reassembled using molecular techniques to spot one case of Covid out of a mixture of 10,000 individuals’ sewage.
When the delta variant will be more widespread in a country, sewage surveillance won’t teach us much about where the virus is, but it could help identify a rise in cases in an area, or a part of the population which might be missed by PCR testing. It could also be used to look for increasing levels of a new variant — the “Delta plus” variant for example — which is now being monitored by public health officials worldwide.
Editor: eesl greece
Green Officer 