A surge in COVID-19 cases involving the delta variant of the coronavirus has Los Angeles County health authorities on high alert and again urging residents to wear masks when they’re inside public spaces.
The county, home to some 10 million people, experienced a 165% increase in new cases compared to last week, the county health department said Thursday. The daily average case rate now stands at 3.5 cases per 100,000 people, an increase from last week’s rate of 1.74 cases per 100,000.
LA County’s daily test positivity rate, which reflects the percent of COVID-19 tests that come back positive, is 2.5%, also an increase from last week’s rate of 1.2%. That’s a sharp rise from the 0.3% positivity rate recorded in the county at the end of May, just before California broadly reopened its economy.
“The new wrinkle in this is really this new variant,” Kirsten Bibbins-Domingo, professor of epidemiology at the University of California, San Francisco, told The Associated Press last week. “It just sort of rips very quickly through people who are susceptible to being infected, which overwhelmingly is people who are not vaccinated.”
Just under 4 million residents in LA County are not yet vaccinated, the county said, which presents a sizable risk. So far, the data for fully vaccinated people suggests the Pfizer, Moderna and Johnson & Johnson vaccines are all effective against the strain in varying capacities.
“The data makes it increasingly clear that vaccines remain the most important tool we have to keep COVID-19 transmission and the incubation of variants low,” LA County Director of Public Health Barbara Ferrer said in a statement.
Overall COVID-19 trends are going in the wrong direction for everyone, and are particularly concerning given the proliferation of the Delta variant. The most powerful way to protect those in hard-hit communities, many of whom are essential workers, is to close vaccination gaps.
The World Health Organization last month identified the delta variant as “the most transmissible of the variants identified so far.”
The Centers for Disease Control and Prevention estimates the strain became the dominant version of the coronavirus in the U.S. in early July, with infections growing rapidly in regions of the country lagging in vaccination rates.
CDC genomic surveillance data from June 6 through June 19, the most recent range available, shows the delta variant makes up 73.3% of all infections in Missouri, 39.7% in Nevada, 36.3% in Colorado and 29.6% in California.