Sewage water tests for COVID-19 suggest 'sixth wave' infection peak has passed in Valencia area of Spain

SEWAGE water analysis in Valencia City is suggesting that COVID-19 cases have peaked in the sixth wave of the pandemic.

Testing doesn’t detect the coronavirusf, but just a very small fragment (about 0.1%) of the virus’s genetic material, called RNA.

Sewage plants send wastewater samples to laboratories who then do a quick analysis of RNA levels in fecal matter.

Valencia has been one of Spain’s pioneers in this analysis which has so far given accurate predictions on the state of the pandemic.

Figures give a head-start of up to a fortnight of what conventional COVID-19 tests end up showing.

In Valencia, 665 million genomic units was reached at sampling points on December 28.

That number fell on Wednesday to 148 million units.

Based on two years of such studies, significant falls in new COVID-19 cases are expected in the next fortnight.

Valencia’s Water councillor, Elisa Valia, said: “The Omicron variant is the predominant one in all of the analysis but since it is such a complicated strain to analyse, it is not possible to determine its exact percentage.”

Water testing cannot confirm individual cases or provide exact details on the cause of COVID-19 outbreaks, but has the big advantage of providing fast results with plenty of immediate samples to go at.

Valia threw in a word of caution that the big fall in coronavirus detections doesn’t necessarily mean the same percentage drop in official COVID-19 cases, though that has been the general direction of travel during the pandemic.

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