Thessaloniki: Indications for re-increase of viral load in wastewater

Indications of a return of the increasing trend in the concentration of viral load of SARS-CoV-2 in the municipal waste of Thessaloniki are seen in the latest daily measurements for the research conducted by the Sewage Epidemiology Team of AUTh with EYATH, in collaboration with the Region of Central Macedonia and of the National Network of EODY.

In fact, as shown in the diagrams presented by APE-MPE (attached), the last measurement of November 23 measures the viral load at the highest level of the current pandemic wave and overall since the beginning of the pandemic. The diagram showing the curve of the course of the measurements in the sewage and the recorded cases begins to show a slight upward trend in terms of the relative stability of the immediately preceding days.

Specifically, in the samples taken daily at the entrance of the Thessaloniki Wastewater Treatment Plant, regarding the rationalized values ​​of relative viral load secretion, the average value of the two most recent measurements, ie Monday 22/11 and Tuesday 23/11 is:

– Stable (+ 7%) in relation to the average value of the two immediately preceding measurements of Saturday 20/11 and Sunday 21/11.

– Increased (+ 24%) compared to the average price of the previous Monday 15/11 and Tuesday 16/11.

“The viral load remains at a very high level and we do not judge this by a daily value, but by cumulatively analyzing the values ​​we measure daily over a longer period of time. Whether what we are seeing now is the peak of the fourth wave – that is, the measurements are slightly increased in the context of fluctuations of a stabilization around the highest level, or the measurements of the next ten days will confirm a clear upward trend to an even higher level, “There is a very large spread of the virus in the community, especially among the unvaccinated citizens, which is pressing and will continue to push the health system and is reflected in the harsh indicators of the pandemic in the city, ie deaths and intubation,” he told APE-MPE. Rector of the Aristotle University of Thessaloniki and scientifically responsible for the research project, Professor Nikos Papaioannou.

Asked to comment on the course of the pandemic curve in the city shown by the daily measurements of the Aristotle University of Thessaloniki in sewage and daily cases, the professor of Chemistry of the Aristotle University of Thessaloniki, Thodoris Karapantsios explained: , as we had hoped from the previous period of relative stability, but fortunately the growth continues at a slow pace. The increase in effluent does not seem to match the relative stability of the cases but the effluent reflects the cumulative secretion of viral load by patients for all days of illness. We had observed a similar discrepancy between sewage and cases in November 2020, where afterwards it seemed that the medical surveillance system was saturated and so no more cases could be detected, while the load in the sewage had a steadily increasing trends.

“We have repeatedly observed a correlation between surges in cargo prices in wastewater with mass rallies and increased mobility in the city. “The two-day moving average shows in detail the fluctuation of the viral load in short periods of time, but we need measurements over a longer period of time to be able to say reliably whether the current signs of slight increase will be followed by an increase or de-escalation,” said the deputy. Molecular Microbiology of the Department of Veterinary Medicine, AUTh, Chrysostomos Dovas.

The coronavirus assessment methodology in municipal waste, developed by the AUTh team, streamlines the measurements of the virus genome concentration based on 24 environmental factors, which may alter the results of the measurements.