All viruses, including SARS-CoV-2, the virus responsible for the ongoing global coronavirus pandemic, change their genetic code, or mutate, slowly over time. While many of these changes have no noticeable effect on the virus’ properties, some can lead to variants which are more transmissible or lead to more severe diseases. To date, the World Health Organisation (WHO) and its associates have flagged five so-called “variants of concern” that have demonstrated either an increase in transmissibility, more severe presentations, or a reduction in the effectiveness of the public health measures used against them. At present, two variants of concern are in circulation — Delta, which first emerged in late 2020, and the faster-spreading but less severe Omicron, which appeared late last year.
The new research was undertaken by microbiologist Professor Ariel Kushmaro of the Ben-Gurion University of the Negev and her colleagues.
They said: “SARS-CoV-2’s continued circulation results in mutations and the emergence of various variants.
“Until now, whenever a new dominant variant appeared, it overpowered its predecessor after a short parallel period.
“The latest variant of concern, Omicron, is spreading swiftly around the world with record morbidity reports.
“Unlike the Delta variant, previously considered to be the main variant of concern in most countries, including Israel, the dynamics of the Omicron variant showed different characteristics.”
In their study, the team used sensitive arrays capable of detecting and distinguishing between different coronavirus variants in wastewater.
People infected with SARS-CoV-2 shed the virus as they progress about their day, allowing viral particles to enter sewer systems through sinks, drains and toilets.
Because of this, analysing the distribution of the virus in wastewater can continue to provide indications of where Covid is active, even as rates of PCR and lateral flowing tests decline.
Prof. Kushmaro and her colleagues monitored the presence of viral particles in the sewage system of Beersheba, in south Israel, from December 2021 through to January 2022, covering the initial Delta–Omicron interactions in the city in real time.
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This model also appeared to indicate that Omicron is burning itself out while Delta is “just biding its time”.
Prof. Kushmaro added: “Of course, there are a lot of factors involved, but our model indicates there could be another outbreak of Delta or another coronavirus variant this summer.”
The research was supported by both the Ben-Gurion University Coronavirus Challenge and the Israeli Ministry of Health.
The full findings of the study were published in the journal Science of The Total Environment.