Highly Contagious Delta Variant of Coronavirus Spreads Rapidly in California

The Delta variant of the coronavirus is now the third most common in California, according to new data, underscoring the danger of the highly contagious strain to people who have not been vaccinated against COVID-19.

The variant constitutes 14.5% of California coronavirus cases analyzed so far in June, up from 4.7% in May, when it was the fourth most identified variant in California, according to data released by the California Department of Public Health. .

Experts say that the Delta variant poses a greater chance of infection for unvaccinated people if they are exposed to it. The variant, first identified in India, may be twice as transmissible as conventional strains of coronavirus. It has been responsible for the recent increase in cases in India, the United Kingdom and other countries.

But vaccinated people are well protected against the Delta variant. A recent study found that the full two-dose course of the Pfizer-BioNTech vaccine was 88% effective against symptomatic disease caused by Delta variant and 96% protection against hospitalization.

There is no general scientific consensus on whether the Delta variant is more likely to cause more serious disease than other strains.

Delta’s surge comes as California’s dominant strain Alpha, first identified in the UK, may have peaked.

In May, the Alpha variant accounted for 58.4% of the coronavirus cases analyzed in California. The proportion of Alpha declined in June, and now represents 37.7% of the cases analyzed, which is still the main variant, but with a much lower proportion.

The Gamma variant, first identified in Brazil, is also being seen more frequently in California. In May, the variant represented 10.1% of the cases analyzed. It now accounts for 21.6% of cases, but Delta continues to grow at a faster rate.

Los Angeles County, the nation’s most populous, has confirmed 123 cases of the Delta variant, 49 of them among Palmdale and Lancaster residents. Fourteen cases of the Delta variant occurred in people from the same household.

Los Angeles County data suggests that vaccines remain overwhelmingly effective in protecting people against the Delta variant, as well as other known variants.

Of the 123 confirmed cases of the Delta variant in the county, 89% of them were among people who were not vaccinated against COVID-19, and 2% among those who were partially vaccinated.

No one has died from the Delta bypass in Los Angeles County.

The few fully vaccinated people who have been infected with the Delta variant “experienced relatively mild illness,” said Los Angeles County Public Health Director Barbara Ferrer.

Almost all of the people who have died in LA County from COVID-19 were not vaccinated.

Data released by the county shows that 99.8% of COVID-19 deaths between December 7 and June 7 were among unvaccinated people.

Cases, Hospitalizations, and Deaths by Vaccination Status in Los Angeles County (June 24, 2021).

“If you are fully vaccinated, you have a lot of protection,” Ferrer said, adding that for the “very small number” of individuals who contracted the Delta variant despite vaccination, “they really did not have a serious illness. … It is a pandemic of unvaccinated people ”.

Results from outbreaks of the Delta variant elsewhere also support the efficacy of vaccines. In Israel, an outbreak of the Delta variant is “driven primarily by the unvaccinated,” tweeted Dr. Ashish Jha, dean of the School of Public Health at Brown University.

Some vaccinated people in Israel have become infected “because no vaccine is 100% effective,” Jha wrote. But infections that are breaking the immunity provided by vaccines are causing mild illnesses.

“What is happening in Israel is that vaccines work exactly as we all expected,” Jha wrote.

In South Africa, President Cyril Ramaphosa on Sunday announced a broad set of new coronavirus restrictions, including curfews and school closings, as the country faces another surge in cases that threatens to surpass the previous two peaks. The Delta variant, first discovered in India, appears to be driving the new surge in South Africa, Ramaphosa said.

South Africa on Sunday recorded more than 15,000 new coronavirus cases, including 122 deaths, bringing its total death toll to nearly 60,000.

Meanwhile, data released by California shows that the percentage of the tested population that has antibodies to the coronavirus – a sign of immunity to COVID-19 – is also increasing.

Between May 16 and June 12, 85.9% of Californians who were screened for antibodies to coronavirus had them, a promising sign of increasing immunity, either from immunization or from exposure. passed to the virus. This figure is higher than the 76.6% calculated over a four-week period in May.

Experts have calculated that between 70% and 85% of the population must have immunity for a region to develop “herd immunity” against COVID-19, which interrupts sustained transmission of the virus.

Authorities continue to urge everyone to get vaccinated against COVID-19, including people who have survived a previous infection. Experts claim that the immunity provided by vaccination is stronger and more durable than immunity from an infection.

The highly infectious Delta variant is making the task of achieving herd immunity difficult.

With conventional strains of coronavirus, 71% of the population needs to be immune for a region to achieve herd immunity and disrupt virus transmission, said UC San Francisco epidemiologist Dr. George Rutherford. But a variant like the Delta – for being so transmissible – would raise that threshold to, for example, 84%, he said.

The Delta variant is also spreading across the country.

Between May 9 and 22, the Delta variant accounted for less than 3% of the coronavirus samples tested nationwide. But from June 6 to 19, that proportion increased to more than 20%.

Dr. Anthony Fauci, the US government’s leading infectious disease expert, called the strain “currently the greatest threat in the US to our attempt to eliminate COVID-19.”

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