Bay Area health agencies track the more contagious Delta variant, as LA county issues mask advisory

There have been mounting concerns over the increasing spread of the Delta strain of the coronavirus, as the variant remained on track to become the most dominant in the U.S. with more cases of the strain being detected across California. 

UNITED STATES - JUNE 16: Beach, Santa Cruz, California (Photo by Carol M. Highsmith/Buyenlarge/Getty Images)

On Tuesday, Santa Cruz County said it’s identified its first case related to the variant based on a COVID-19 sample collected on June 10. The patient was described as a man in his 50’s who experienced mild symptoms. 

"A case investigation is underway; however, it is very likely there are additional undetected cases of the Delta variant within Santa Cruz County," health officials warned. 

While officials did not say whether the man was vaccinated, they did stress, "Complete vaccination is highly effective against the Delta variant." 

The Delta strain was believed to be the most contagious of the COVID-19 variants that have emerged thus far and may lead to more severe symptoms. 

New figures from the Centers for Disease Control and Prevention (CDC) showed that the strain was now responsible for about one in every five new infections, a sharp increase from about one in every 10 the week before.

In a briefing last week, National Institutes of Health Director Dr. Anthony Fauci declared, "The Delta variant is currently the greatest threat in the U.S. to our attempt to eliminate COVID-19." 

In California, statewide figures showed 372 cases related to the Delta strain.

Concerns over the variant prompted Los Angeles County’s health department on Monday to issue an alert strongly advising residents to wear a mask in indoor public places, regardless of their vaccination status. Health officials said recent figures showed that new cases of the Delta strain made up almost half of all variants sequenced in Los Angeles County. 

SEE ALSO: LA County Public Health strongly recommends masking indoors amid Delta variant concerns

In the Bay Area, health agencies have not issued any such recommendations as of yet, but local health officials have been closely tracking the spread and they said that the fast movement of the variant highlighted more than ever the importance of getting vaccinated.

In Contra Costa County, health officials told KTVU, "While we are not changing our recommendation at this time, we are concerned about ongoing transmission in our county, especially amongst the unvaccinated population." Health officials strongly urged unvaccinated residents to follow state mask rules, adding that it supported "any vaccinated individuals who want to take extra precautions and continue to wear masks."

In Alameda County, which has seen 52 Delta variant cases since mid-April, health officials also said that the county remained aligned with California's mask mandate. As of June 15th, the state lifted mask requirements for those who have been fully vaccinated, with a handful of exceptions including on public transit and in health care settings. Masks continued to be required for those who have not been fully vaccinated.

"Vaccination remains the best protection against severe illness, hospitalization and death due to COVID-19," said Neetu Balram, the public information manager for Alameda County Public Health. She also stressed that to get the full benefits of the vaccine, it’s critical to follow through with the second dose for those who received the Pfizer or Moderna vaccine.

Health officials in San Francisco and across the Bay Area echoed the same message as they tracked the Delta variant. 

"Vaccinating as many people as possible, as soon as possible, is our best defense against COVID-19, the Delta variant and the harm it can do to our communities," officials with the San Francisco Department of Public Health (SFDPH) told KTVU, noting that the vaccines have proven to offer protection against the virus and its variants. 

The health department also said that while San Francisco has among the highest vaccination rates in the country, with more than 70 percent of its eligible population fully inoculated, there were communities in the city where vaccination rates were much lower, putting those residents at increased risk given the new strain. 

"We are working closely with state health officials to understand the risks of the Delta variant. We know that it is present in the state and the Bay Area, and we continue to align with state guidance that states that people who are not yet fully vaccinated are required to wear masks indoors or at large outdoor events," San Francisco health officials said.

But officials noted that it was prepared to make adjustments to the current guidance if needed. "We continue to follow emerging data and science and will adjust this approach to expand masking recommendations, if necessary," SFDPH officials said. 

Some Bay Area counties, including Santa Clara and Sonoma, have begun reporting cases of specific variants along with its COVID-19 data. The Delta strain has shown up in 59 cases in Santa Clara and 19 in Sonoma County, according to the respective counties' health department websites. 

Santa Clara County health officials pointed to its high rate of vaccinations for providing protections to the community. "While we recognize that masks are effective in reducing transmission and are especially valuable in crowded, poorly ventilated indoor spaces, at this time, we are not reimposing a community-wide masking requirement," officials said, adding, "Nevertheless, the County is closely tracking the Delta variant, as we do all variants of concern." 

In updated information on June 17, the California Department of Public Health identified the strain as a "variant of concern," following similar announcements from the CDC and the World Health Organization. The state has been tracking cases of known variants through genomic sequencing and the data showed the Delta strain was detected in California in April. 

"B.1.617.2 (Delta) variants are associated with increased transmission," state health officials stated, adding that it "May have moderately decreased response to antibody treatments."   


In Marin County, which has been widely recognized for its high rate of vaccinations, with more than 83 percent of eligible residents fully vaccinated, health officials confirmed that the Delta variant had been detected there too. A sampling of recent cases showed about 65 percent stemmed from the Delta variant. Figures showed that in the past 14 days, the county has seen 44 new cases overall and officials noted that the 65 percent represented just samples returned in the past month. 

The county said that while at this point, it continued to remain aligned with the state on its mask recommendations, it would be prepared to implement any changes if the state health department signaled the need to return to more restrictive rules. 

Marin County Health Public Information Officer Laine Hendricks told KTVU that while there were still residents who have not been vaccinated, the high rate of those who have received their shots were clearly providing protections to the entire community. 

"Thankfully, because of Marin’s growing vaccination rate, where we do detect the presence of the variant, the cases die out versus spreading, because we’re beginning to see the benefits of community immunity," Hendricks said. "The message at the end of the day? Vaccines have proven their effectiveness and this is yet another reason for residents to consider vaccination."