Scientists at the University of California, San Francisco (UCSF) found that the B1427 and B1429 variants caused a two-fold decrease in neutralizing antibodies. The South African B1351 strain, another "variant of concern," reduces antibody activity by as much as six times. Furthermore, the California strains became the prevalent variants within a six-month span. They represented most cases found in UCSF hospitals and clinics and medical facilities in the Alameda and Santa Clara counties.
According to the UCSF scientists, the B1427 and B1429 variants are about 20 percent more infectious than the original virus strain. This is because they possess four unique mutations, including three that change the shape of the pathogen's spiked protein. The Wuhan coronavirus uses this spike protein to latch itself to cells and enter the body, where it multiplies.
Earlier studies have linked the California strains to a higher risk of severe disease and death. They have also been attributed to longer stays in intensive care units and higher need for mechanical ventilation. However, the scientists' findings have raised alarm bells: People who received monoclonal antibodies or convalescent plasma treatments saw their COVID-19 blood antibody levels dwindle as much as 6.7 times following infection with both strains.
It is not known where the two variants came from, but they have been reported in 44 states – with most cases in California, Nevada and Arizona. Back in January, a key mutation called L452R was found in more than half of the total COVID-19 cases in San Francisco's Mission District.
The discovery of the B1427 and B1429 strains comes as the Golden State is experiencing a drop in hospitalizations and deaths. Experts have remarked that social distancing, face masks and vaccination have played a key role in controlling the virus's spread as it evolves. But the findings of the USCF scientists raise concerns about a potentially higher risk of re-infection among vaccinated people – especially those whose bodies produced little antibodies after getting the jab.
Dr. Charles Chiu of UCSF said existing COVID-19 vaccines will likely remain effective against the new strains. However, he added that the California variants' growing prevalence and ability to reduce immune protection means they must be monitored closely. Thus, his laboratory is working with the California Department of Public Health to find cases of the new variants. (Related: CDC declares 2 coronavirus strains from California to be "variants of concern".)
"I don't think it's going to lead to a 'vaccine breakthrough' where the vaccine doesn't work. But this … gives us [an] initial idea of the infectivity and the potential resistance to neutralizing antibodies for [variants] that, up until now, [have] not been studied," Chiu commented.
It is hard to determine what the USCF scientists' findings mean when it comes to the effectiveness of vaccines and other COVID-19 treatments in protecting people from the strains. The Wuhan coronavirus makes tiny changes in its genome as it reproduces, and understanding this evolution and the mutations that cause changes in its behavior is key to understanding the threat of new strains. The virus's genetic makeup, stored in a single RNA strand, determines whether treatments or vaccines meant to address it will work or not.
The Food and Drug Administration (FDA) moved quickly in response to the California strains' purported effect on those who received antibody treatments. It halted shipments of the Eli Lilly drug bamlanivimab into California, Nevada and Arizona due to concerns it may be less effective against the new variants. FDA Acting Commissioner Dr. Janet Woodcock confirmed the move during a March 17 webinar with the American Medical Association.
However, the FDA's move did not affect another monoclonal antibody drug made by Eli Lilly. Its other COVID-19 treatment – a combination of bamlanivimab and etesivimab – significantly reduced the risk of hospitalization and death in early trials. (Related: Eli Lilly monoclonal antibody drug trial paused over safety concerns.)
An Eli Lilly spokesperson said in a statement that the pharmaceutical company recognizes the U.S. government's decision to "no longer allow direct ordering of bamlanivimab alone in California, Arizona and Nevada due to … the prevalence of the [new variants]." The statement also reinforced the positive impact of Eli Lilly's combination drug treatment for COVID-19, saying the two drugs in tandem "maintains [a] neutralizing effect against [the California strains]."