It appears that coronavirus concentrations in Gothenburg wastewater may now be reflecting a partly new community pattern of contagion. Researchers at the University of Gothenburg are monitoring the trend, which may be heading for a lowest level of virus concentrations that is several times higher, between flatter peaks.
“We seem to be seeing a different pattern of spread now than before,” states Heléne Norder, adjunct professor of microbiology at the Department of Infectious Diseases at Sahlgrenska Academy, University of Gothenburg, and microbiologist at Sahlgrenska University Hospital.
Norder leads the group of virologists at the University’s Institute of Biomedicine who have been investigating the presence of SARS-CoV-2 in wastewater since February 2020. Their surveys are carried out in collaboration with the municipally owned company Gryaab, which treats wastewater in Gothenburg and the surrounding municipalities, and sends the scientists one sample a week, composed of samples collected daily.
Raised virus levels in wastewater, and thus increased incidence of disease in society, can predict workload peaks in health care to varying degrees. This is obviously interesting, ahead of major national public holidays.
More even virus concentration levels
“The levels have declined slightly since last week and we don’t have any large cluster spreads. There’s probably a more even spread in society now — a pattern we probably have the vaccinations to thank for,” Norder says.
“At the same time, our results indicate that more people are getting infected, as the rise in the minimum level shows. There are small peaks, but above all the trend is steadier between peaks. What can be expected is for the figures to hover around the new baseline, three to four times higher than the annual average.”
One explanation, Norder thinks, may be that more vaccinated people are getting infected — people who do not excrete very large quantities of the virus and, accordingly, do not contribute to high peaks. She hopes that the steadier virus concentration level will also result in a more even influx of patients into health care. Care providers and the Infection Control Unit in Region Västra Götaland are receiving regular reports and monitoring the trend.
Influenza and norovirus underway
For about a month, the researchers have also been measuring and analyzing the two types of influenza virus, A and B, in the wastewater. These studies also include norovirus, which causes the "winter vomiting bug", and the respiratory syncytial virus (RSV), which causes respiratory infections and can make young children seriously ill. The research group at the University of Gothenburg is a forerunner in these particular measurements and analyses.
The latest measurements make it clear that there is also currently a flu epidemic: the prevalence of Influenza A is high and even, while measuring that of type B was not feasible. There are rising levels of norovirus, too, while RSV concentrations are very low.