California coronavirus variant may be more infectious, could cause more serious illness, SF studies show

Separately, a study by Dr. Charles Chiu of UCSF also found evidence that the variant is more infectious. In addition, her team found that people infected with the variant were more likely to end up in intensive care or die. And lab tests have shown the variant to be less sensitive to antibodies produced by people who had previously been infected. It is not clear from the results whether the variant is less susceptible to vaccines.

It “should probably be singled out as a variant of concern warranting urgent follow-up investigation,” Chiu and a team of authors wrote in an article on the study. The two studies have not yet been published.

“We don’t want to be alarmist. It’s not as aggressive as the UK variant, ”said Joe DeRisi, Biohub co-chair, of the Mission District study results. The UK variant, known as B.1.117, is believed to be around 50% more infectious than the original virus from China. “But it underscores the need to look at this strain more carefully and do more studies on it. We need to be aware that it is in the community and that it is spreading quickly. “

Chiu, however, said that further study might actually show that the California variant is about as contagious as the UK’s.

“This variant should be treated with the same level of concern as the other variants,” Chiu said in an interview on Monday. “I’m actually quite worried about this particular variant. This is essentially the majority of cases now across California. “

Coronavirus variants have become of growing concern in the pandemic as mutated versions of the virus emerge around the world that are more infectious, cause more serious illness, or are partially resistant to vaccines. Public health officials are rushing to vaccinate large swathes of the country, in part to reduce cases and prevent the virus from mutating.

Infectious disease experts first became concerned about the California variant in January, when two teams of scientists – one at UCSF and one in Los Angeles – independently identified it as rapidly spreading in a few communities, including some in the bay area. The variant was found to be the source of a major outbreak at Kaiser Permanente in San Jose in which more than 90 people were infected.

There has been some confusion over what to call the California variant, which is actually two separate but very similar variants that share the same key mutations. The California Department of Public Health calls them B.1.429 and B.1.427, but both variants are also referred to as CAL.20C or sometimes referred to by a single mutation, L452R.

This mutation is the key to the Californian variant. It’s located on the spike protein – a place on the virus where it attaches to human cells. Due to the location, the L452R mutation is believed to make the virus more able to stick to human cells, thereby making the variant more infectious.

Chiu’s study used several techniques to determine how infectious the California variant is and whether it causes more serious disease or may be resistant to an immune response, either through vaccination or through a previous infection.

His team found that the variant appeared to spread faster in outbreak situations. In addition, the virus was more highly concentrated in samples taken from individuals infected with the variant. Both are signs of increased contagiousness. Scientists also found the variant to be more infectious in laboratory studies.

Research has also shown that the variant was associated with a higher risk of being put on a ventilator, treated in intensive care, and dying. But Chiu said the number of hospitalized cases her team looked at was relatively low and more study is needed to be sure that the variant causes more serious illness.

The team also looked at the immune response mounted against the variant by people who had been vaccinated or had previously been infected with the coronavirus. The variant was resistant to some antibodies from both groups – a sign that the vaccines might be weakened somewhat and people might be prone to reinfection with the variant.

But Chiu said he believed the vaccines would remain effective. “Overall, the vaccine responses are pretty strong,” he said.

The research on the mission district was coordinated by Unidos en Salud, a collaboration between Chan Zuckerberg Biohub, UCSF, the San Francisco Department of Public Health and the Latin Task Force for COVID-19. The group has operated a rapid coronavirus test site in Mission district since August, and scientists have been working with the community to report on how the virus is spreading there.

DeRisi noted that more research needs to be done to determine how much more infectious the variant is and under what conditions. This new evidence should remind people to be “a little more careful” in preventing infections, even as cases continue to decline, he said.

“While it’s good that the positivity rate is dropping really quickly and everyone is applauding the vaccine, that doesn’t mean we should relax our protections now. Because these are things that could spread faster and potentially have some benefit, even in an individual vaccinated to some extent, ”he said. “Now is not the time to let your guard down.”

For the mission study, scientists looked at nearly 8,900 tests from January 10 to 27. About 800 tests turned out positive and scientists performed genomic sequencing on about 630 of the positive samples. They found that the California variant made up 53% of the samples – a big increase from the Mission’s last genomic sequencing batch before Thanksgiving, when the variant only made up 16% of the samples.

Then, scientists and public health officials investigated positive cases to determine how the variant spread in Mission households. The attack rate in households is a common way to determine the degree of infection of a virus.

Scientists found several other potentially worrying mutations in the mission’s results, including one person infected with a variant outside of Brazil called P.2. This variant is not the disturbing P.1 that has spread widely in parts of this country, but the P.2 variant carries a mutation that can make it partially resistant to vaccines. DeRisi said the person infected with the variant did not appear to have passed it on to anyone else.

The team did not find any of the UK or South African variants, both of which have been identified in other parts of the state.

DeRisi said that regardless of the mission’s study, the Biohub earlier this month identified a new variant in a nursing home outbreak in Humboldt County. This variant had a mutation found in other variants which is known to make the virus more infectious. But the mutation appears to have arisen randomly in the nursing home, public health officials said.

“Variants of the coronavirus are going to appear all the time. It’s always a question of which variants should I worry about. Which ones matter, ”DeRisi said. “Each mutation is the one you put on your leaderboard and watch.”