Covid test positivity in California is up 47.6% in the past week, according to the California State data dashboard. One week ago, the 7-day daily test positivity rate was 2.1%. Today, it sits at 3.1%. That’s quite a jump for a metric that is averaged over seven days to account for daily fluctuations in data reporting and testing.
The rise comes as a new version of Omicron, a subvariant of BA.2 called BA.2.12.1 is making inroads in the region and across the country. The sublineage is thought to have a 23%–27% growth advantage over BA.2, according to the New York State Department of Public Health.
Nationally, BA.2.12.1 now accounts for 19% of all new cases specifically sequenced for variants in the country, according to data released Tuesday by the U.S. Centers for Disease Control. That means the strain — barely on the national radar two weeks ago — is now being identified in close to 1 in 5 newly-sequenced cases.
California, however, does not break Omicron data out into sublineages, a practice that made it hard to track the rise of BA.2 and is now making it hard to chart BA.2.12.1, since all Omicron — which accounts for 99.2% of the state’s cases — is lumped in together.
But reporting indicates that in the southwestern region made up of California, Nevada and Arizona, BA.2.12.1 is responsible for about 9% of new cases. That data, however, is over a week old. The subvariant’s share of cases has likely grown. Whether or not BA.2.12.1 is driving infections in California is unclear. But something is.
The last day for which complete daily case data is available on the California Covid data dashboard is April 13, which saw 3,674 new infections.
California now only reports new cases in a lump sum two times a week, and then backdates the numbers over the following weeks. The most recent lump-sum report was posted today.
The three-day cases total reported by California today is 15,747. That averages out to 5,297 a day. That’s a 42% rise in nine days — since April 13 — which roughly parallels the rise in test positivity. Of course, the number of tests reported in the state continues to fall, so the raw number of cases is likely to be higher.
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