California: The Omicron strain of the coronavirus was detected in California's wastewater last month, even before the World Health Organization declared it a "variant of concern," lab data suggests.
In a statement to The Times, the California Department of Public Health said that a sample of wastewater collected in Merced County on November 25 contained a mutation that suggests the Omicron variant was present in California at that time.
That's one day after South African scientists informed the World Health Organization of the new variant, and a day before the WHO gave it the name Omicron and declared it the newest coronavirus variant of concern.
The finding reinforces observations that scientists have made in recent weeks: that Omicron was rapidly spreading across the world even before global health officials were aware it existed.
There are other examples that indicate Omicron was in California even before the WHO gave the variant its Greek-letter designation and raised the alarm on November 26.
The first Omicron case identified in the US, in a San Francisco resident, returned home November 22 from a trip to South Africa and became symptomatic on or around November 25 — Thanksgiving Day.
Los Angeles County's first verified Omicron case was detected in a traveller who also returned on November 22 after a trip to South Africa via London.
Sampling wastewater for coronavirus-related particles is being used to track pandemic trends.
In California, several groups of scientists are monitoring wastewater for coronavirus samples, including experts affiliated with Stanford University, UC Berkeley, UC Davis, UC Merced, UC San Diego and the state Department of Public Health.
A Stanford group reported to the state that it detected a mutation suggestive of — but not specific for — Omicron in wastewater not only in Merced County, but also Sacramento County, the Department of Public Health said in its statement.
The samples were retested and confirmed using a second, more specific lab procedure indicating the variant is likely present in Sacramento and Merced counties, state officials said.
There have been at least 14 confirmed Omicron cases identified in California, with six in Alameda County, five in Los Angeles County and one each in San Diego, San Francisco and Yolo counties.
Although there's been a scattering of cases, there have been no Omicron outbreaks in the state. Officials have said that early indications are the variant is highly transmissible, but it might not cause as severe illness as the Delta variant.
The findings come as health officials from a number of California counties say they're seeing early signs of a rebound in coronavirus cases related to Thanksgiving, which some worry could be the beginning of the state's fifth COVID-19 surge. Those cases are connected to the Delta variant.
It's still far from clear whether California will see a significant spike in cases this winter or if the combination of relatively high vaccination rates and various safety rules limit the scope of a surge.
But there are already warning signs.
Statewide, the daily average of newly reported infections has risen more than 30 per cent since before Thanksgiving. The number of Californians hospitalised with COVID-19 also has climbed during that time, interrupting weeks of mostly steady declines.
In Los Angeles County, weekly coronavirus case rates have climbed by 33 per cent over the last two weeks, sending the nation's most populous county back into the worst coronavirus transmission tier, coloured red on maps published by the US Centers for Disease Control and Prevention.