Numbers Still Small, But More Transmissible Delta Variant Grew Nearly 30% Last Week In California

Numbers Still Small, But More Transmissible Delta Variant Grew Nearly 30% Last Week In California

In the same week that Gov. Gavin Newsom dropped capacity limits, social distancing rules and most masking requirements across the state, the so-called Delta variant of Covid-19 increased nearly 30%. The state last week also declared Delta a “variant of concern” for the first time.


The strain had previously barely registered on the weekly new variants count posted by the CA Department of Public Health. But on Thursday, the number of cases related to Delta and related variants discovered in the state rose from 286 to 399. That’s a 28.6% rise week-over-week. The total is, of course, still tiny compared to the 3 million-plus infections from other strains in the region.

But as U.K. leader Boris Johnson extended his country’s lockdown due to the rapid spread of Delta, it was projected to become the dominant variant in the U.S. this summer. The Delta variant and related Kappa variants are involved in massive outbreaks in India. The CDC estimates the Delta variant accounted for about 10% of new cases in the U.S. last week. It is thought to be at least 60% more transmissible than the original strain that spread across America.


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In California, it’s not just the variant of concern numbers that have ticked up. The 7-day test positivity rate which hit the all-time low number of 0.7% on June 5, has risen steadily to 1% over the past two weeks in the state. It’s the first sustained rise in that key Covid-19 indicator since the worst of the pandemic in January.


Between late April and early June, 64 cases of Delta-related infections were identified among residents of L.A. County, with most of them identified in the last few weeks, health department data indicated. Much of the transmission of this variant appears to be occurring within households. What’s more, with only a fraction of positive test results examined to determine which variant caused them, the real number of Delta-related infections is likely to be much greater.


L.A. Public Health Director Barbara Ferrer said on Saturday that the county is seeing a slow but steady rise in the local number of Covid cases involving Delta.


“We’re especially concerned about this variant because it appears to be highly transmissible, and by that we mean it’s more contagious, even than other highly contagious Covid variants,” said Ferrer.

“It’s also thought that this variant may cause more severe infections than other Covid variants. And while fully-vaccinated people appear to be very well protected from infections with Delta variants, people with only one vaccine [doses] are not well protected at all.”


With social distancing, capacity and most mask restrictions lifted in workplaces, Ferrer warned there is an increased risk for spreading variants of concern.


“Currently, this is a pandemic of unvaccinated people who are at increasing risk for unknowingly incubating Delta variants and other variants of concern,” Ferrer said. “At home, unvaccinated people may be able to control their risk by determining who enters their physical environment and from what distance they interact. However, unvaccinated workers at job sites often lack that kind of control.”


City News Service contributed to this report.