Unvaccinated people are continuing to spread the highly contagious delta variant of COVID-19 across Los Angeles County, and with current inoculation rates officials say they don’t expect the region to reach herd immunity before fall.

The prevalence of the delta variant — which was first detected in India and is more infectious and potentially more deadly than all other variants — is increasing each week in L.A. County.

The county has detected 64 delta cases since April, indicating the variant is widespread since only a small percentage of infections are sequenced, Hilda Solis, chair of the county Board of Supervisors, said in a media briefing Monday afternoon.

“You’re more vulnerable than ever for getting COVID if you are exposed to the strain, and this is especially true with masking and distancing requirements relaxed,” Solis said.  

Early studies indicate the delta variant is 50% more contagious than the Alpha variant first found in the U.K., which was already up to 80% more transmissible than the original COVID strain. However, studies have shown that vaccines remain effective against the delta variant.

“Currently, this is a pandemic of unvaccinated people who are at increasing risk for unknowingly incubating delta variants and other variants of concern,” county public health Director Barbara Ferrer said.

Ferrer noted that of those fully vaccinated in L.A. County, only about 0.4% get infected with COVID-19, around 0.003% are hospitalized and just 0.0004% die of their infections.

As of Monday, 67% of L.A. County residents age 16 and older had received at least one dose of vaccine, and 58% were fully vaccinated, officials said.

But the current vaccination rate is lower than public health officials would like, and Ferrer said she now doesn’t expect the county to reach herd immunity by fall. The county says at least 80% of people need to be vaccinated to halt the virus’ uncontrolled spread.

Earlier this month, Ferrer had predicted herd immunity could be achieved by late August.

“It’s just going to take us time, and it’s going to definitely take us the whole summer at this point to get to full immunity,” she said Monday. “But we would definitely like to be in a place where community immunity is possible as we enter the fall.”

And while vaccination rates are higher among the general population, only 43% of Black residents and 51% of Latinos age 16 and above have received at least one dose.

“The delta variant may again create a tale of two counties if residents do not get vaccinated,” Solis said, referring to the high infection rates that ravaged communities of color during the winter surge.

Meanwhile, hospitalization, case and death rates remain highest among Black Angelenos.

As of May 15, there were 46 positive cases among every 100,000 Black residents with much lower numbers among Latinos, whites and Asians. A month later, case rates have dropped among all residents, but still remain highest among Black residents, with a case rate of 40 per 100,000 people.

“While the case incidence rates decreased in white and Asian populations by about one half to one third, they decreased by only 15 to 25% in Black and Latinx populations,” Ferrer said.

And while the death rate among Black residents decreased by about three-quarters, it’s now four times higher than the death rate among Asian residents and twice as high as that of white residents.

“The disproportionate suffering that’s borne by the communities that have already suffered the most is deeply concerning,” Ferrer said.

The public health director vowed to continue outreach work in underserved communities for “however long it takes” to close the gap in vaccination and death rates, saying “this is going to be the work for the summer.”