Two cases of a coronavirus variant found for the first time in South Africa that reduce the effectiveness of some vaccines have been identified in the Bay Area, in Alameda and Santa Clara counties, Governor Gavin Newsom said on Wednesday.
These are the first two cases of this variant, called B.1.351, found in California. They were identified by scientists at the Stanford Clinical Virology Laboratory on Tuesday night and reported to the state on Wednesday morning.
Variants that are more infectious or reduce the vaccine’s effectiveness pose a threat to the state’s ability to control and end the pandemic quickly, public health officials said. More than 150 cases of a variant first identified in the UK that is known to be more infectious have been found in California, including the counties of Alameda and San Mateo.
Another pair of closely related variants identified in California have spread rapidly in the bay area and southern California. Scientists believe that these variants respond to vaccines, but are now testing to determine whether they reduce effectiveness. They are also studying whether the variants are more infectious.
The South African variant is considered of particular concern because studies have found that it is able to partially prevent the body’s immune response, whether it is generated by a vaccine or previous infection with the coronavirus. So far, vaccines appear to prevent serious illness and death from the variant.
“The British variant is still susceptible to vaccines and will spread anyway. But let’s put this one back in the box, ”said Dr. George Rutherford, an infectious disease specialist at UCSF.
As of Tuesday, nine cases of the South African variant have been identified in three states, according to the Centers for Disease Control and Prevention. That figure did not include the new California cases.
“These variants are here,” said Alameda County Medical Director, Dr. Nicholas Moss, at a press event on Wednesday. “We must prepare and plan accordingly.” As relatively few cases of coronavirus are genomically sequenced, he said, “we have only a very limited picture of their local spread.”
The two vaccines currently available in the United States, made by Pfizer and Moderna, provide some protection against B.1.351, but perhaps less than the initial virus in China for which they were designed.
The Modern vaccine induced a six-fold lower immune response against the South African variant compared to previous variants, the company said in late January after conducting a small study. But even that lower level of immune response, or neutralizing antibodies, is probably enough to protect against COVID-19, the company said.
Still, Moderna is testing a booster vaccine to see if it can provide more immunity.
Likewise, the Pfizer vaccine also induced a slightly lower level of neutralizing antibodies against the variant, but it should still be sufficient to protect against COVID-19, according to studies by Pfizer and the University of Texas Medical Branch. The difference is “unlikely to lead to a significant reduction in vaccine effectiveness,” said Pfizer.
South Africa recently stopped using a vaccine made by AstraZeneca due to reduced effectiveness. This vaccine has not yet been approved for use in the United States. South African scientists also said that people who were previously infected with other variants of the coronavirus appear to be susceptible to reinfection with the new one.
Moss, from Alameda County, expressed optimism about vaccines. But in the meantime, he said, “We need to stick to the things we know are working for now. That means covering your face, keeping your meetings apart and limiting.”
“The most important thing with the variants is to limit the amount of COVID that exists,” he added.
The San Francisco Chronicle editors Aidin Vaziri and Catherine Ho contributed to this report.
Erin Allday is a writer for the San Francisco Chronicle. Email: [email protected] Twitter: @erinallday