Spain investigates the expansion of omicron in its wastewater

There are two ways to monitor the spread of the pandemic: look at the photograph taken by the diagnostic test results or look at the image that the sewage water. The first method collects information about people who, for one reason or another, have had the suspicion of being infected and have carried out a diagnostic test. The second, on the other hand, shows an overview of the presence of this virus in the population (which also includes information on asymptomatic and undiagnosed). In these weeks, while Spain has confirmed the first cases of the omicron variant in the territory, treatment plants throughout the country are working to understand how widespread it is this emerging lineage.

“In recent weeks, in Spanish wastewater only the presence of the delta variant has been seen … because we still did not know that we had to look for omicron”, he explains Francisco Javier Sánchez Martínez, deputy director general of water protection and risk management of the Ministry for Ecological Transition. As the expert explains, since the World Health Organization (WHO) noted this variant as a cause for concern, “labs are working tirelessly to ‘fine tune the machinery ‘ that allows to analyze the presence of omicron in Spain “.

“The laboratories are working tirelessly to ‘fine-tune the machinery’ that allows analyzing the presence of omicron in Spain”, Francisco Javier Sánchez Martínez


In recent weeks, Sánchez Martínez argues, it is possible that the analyzes of the wastewater showed a watery result. Especially because, after the rains that in recent days have affected a large part of the peninsula, rain has diluted the concentration of viruses in the water. Now that the good weather has returned, the technicians of the Ministry and the autonomous communities are working to carry out the first analysis that could show the real presence of omicron in Spain. If all goes well, the first report on the matter could be published in the middle of next week, after the December bridge.

“Hopefully we don’t find anything”

“If traces of omicron are found, everything indicates that it will be in very small concentrations. That is, let’s hope that there is a preponderant presence of the delta variant and only a pinch of omicron. But the truth is that I hope we don’t find anything. Hopefully the expansion of this lineage is still something very anecdotal in Spain, “says Sánchez Martínez in an interview with El Periódico de Catalunya.”Catalonia you have already found some signs that point to the presence of omicron, but it’s still too early to confirm. We will have to wait at least for next week’s report to have solid evidence whether omicron is here or not, “he adds.

If traces of omicron are found, everything indicates that it will be in very small concentrations


As this expert explains, if next week’s analysis only finds isolated samples of omicron in Spanish sewage, it is most likely that there are still very few people infected by this variant in the country. On the contrary, if the study found large presences of this virus in national treatment plants, it is possible that, beyond the handful of confirmed cases in recent days, we are already facing some level of community transmission of omicron in Spain.

The world also looks to its wastewater for evidence of omicron expansion. On India and USAFor example, different research teams have already announced specific programs to track the presence of this variant through its treatment plants. In the old continent, the European Commission convened this Friday all the experts from the different member states to fine-tune the technology necessary to detect these types of mutations. The result of these studies, experts say, will be key to designing measures to stop the expansion of this lineage that for weeks has kept the world in suspense.

A laboratory studies the collected wastewater samples to study the evolution of the covid-19 pandemic in Spain. EPC

More control points

It has been a year and a half since treatment plants have become one of the main mechanisms of control of the pandemic in Spain. “The most important and the most precise are the data provided by clinical analyzes, such as antigen tests and PCR, which is what allows obtaining such relevant information as the number of infected and the accumulated incidence. The study of waters does not replace this, but does provide a key safety net to know the health condition of the cities analyzed “, says Sánchez Martínez, as spokesperson for the state project ‘Vatar-covid-19‘, in charge of microbiological surveillance of the coronavirus as an epidemiological indicator of the pandemic in Spain.

The study of the waters provides a key safety net to know the health status of the cities analyzed


The project started in July 2020. Since then “every week, on the same day and at the same time“Wastewater samples are collected from dozens of Spanish treatment plants which, in turn, have been selected by Health and the autonomous communities as reference points to have a representative sample of the Spanish population. “Before collecting samples, keep in mind that each city has a different life. It is not the same to collect a water sample first thing in the morning on a weekday as on a holiday, when people get up later and change their routine, “says Sánchez Martínez to put the question into context. project complexity and the multiple factors that can affect the reading of the results.

Collection of a water sample in a Spanish treatment plant. EPC

The program started with 38 treatment plants. A few months ago, the European Commission asked member states to expand this monitoring system in all cities with more than 150,000 inhabitants. In Spain, this would be equivalent to about forty points. “Between the end of this year and the beginning of next year, we want to extend the program until reach about 60 treatment plants“, explains Sánchez Martínez in statements to this newspaper. The objective, detailed from MITECO, is collect up to 3,960 wastewater samples to track the spread of the coronavirus.

Emergent Variant Tracking

In October, the project also began to track the presence of the different variants of coronavirus in Spanish sewage. “The ‘original coronavirus’ that emerged in Wuhan is practically no more. From October until now, the delta variant has been the predominant throughout Spain”, Says a spokesperson for the ‘Vatar-covid-19’ project. “This type of study is very complex because we do not find complete samples of the virus, but rather we look for specific targets of each lineage to measure the presence of these variants in the territory, “he clarifies.

In the coming weeks, moreover, everything indicates that one more phase of this project will be deployed. “The emergence of the omicron variant has shown that, beyond looking for the lineages that we already know, it is necessary to make a active surveillance of emerging variants. For this reason, once a month we will do a ‘general sweep’ of how the virus genome is doing in wastewater to identify possible new variants and mutations, “explains Sánchez Martínez. The first pilot test of this project could be carried out in just 15 days and will have around 1,000 samples collected throughout Spain.


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