There is a real danger of another international wave of COVID this summer, with the Delta variant possibly set to make a comeback, new Israeli research suggests.
The peer-reviewed study is based on state-of-the-art Israeli sewage monitoring, which reveals not only the prevalence of coronavirus cases, but also its variant.
It showed that even at the height of the Omicron wave, the previous Delta The variant had not been removed, although it was expected to build on the dynamics of previous waves.
After monitoring the patterns of the two variants, the researchers concluded that Omicron and its sub-variants are likely to die out soon, but Delta has shown such strong resistance that it may well make a comeback.
“Our findings highlight that the pandemic is not over and suggest that sooner or later there will be another wave, possibly in the summer or late summer,” said Professor Ariel Kushmaro, who heads Ben-Gurion University of the Negev. sewage laboratory that conducted the investigation, he told The Times of Israel.
He said the importance extends far beyond Israel and indicated that, internationally, Delta still poses a greater threat than is widely assumed. Delta could reemerge in its current form, or it could spread as a new subvariant, he predicted.
Some COVID experts say the study provides a clear basis in the data for a warning they have been giving for weeks.
“The pandemic is not over, and this great research provides clear findings that emphasize this and help us understand the situation,” immunologist Dr. Yariv Wine, an academic at Tel Aviv University who was not involved in Ben-Gurion’s research. he told The Times of Israel.
Kushmaro said Delta’s resilience surprised his team. “Before we saw that when one variant rises, others disappear; but this just doesn’t seem to have happened with Delta, which seems to have some survivability,” he said.
“In this study, we identified that even when Omicron was at its highest in wastewater, Delta was still circulating,” he added. “The patterns we see indicate that Omicron is on the way out, but Delta has survived and is poised for a possible resurgence.”
Kushmaro and colleagues, including Dr. Karin Yaniv, wrote that based on their analysis model, Delta is expected to continue to circulate largely undetected, what they call a cryptic circulation, until it triggers a wave. They published their findings in the journal Science of the Total Environment.
“Based on the model developed, Omicron levels can be expected to decline to elimination, while the Delta variant will maintain its cryptic circulation,” they wrote. “If this happens, the aforementioned cryptic circulation may result in the resurgence of a wave of Delta morbidity or the possible generation of a new threatening variant.”