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[时事新闻] Rapid spread of U.K. coronavirus variant in Southern California sparks alarm

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发表于 2021-2-2 09:36:59 | 只看该作者 回帖奖励 |倒序浏览 |阅读模式


The growing numbers of cases of the highly contagious coronavirus variant first identified in Britain are sparking worry about a future surge in Southern California, one of the nation's two hot spots of the worrisome new strain.
© Provided by The LA Times Valerie Dunlap, 67, left, of Granada Hills, and Cookie Lewis, 68, right, of Valley Village, make their way with others in the by-appointment-only line to get vaccine shots to protect against the coronavirus at the Balboa Sports Complex in Encino. (Mel Melcon/Los Angeles Times)
Scientists are increasingly voicing deep concern that it is essential to keep coronavirus transmission low and ramp up vaccinations quickly, saying it is possible that hospital systems could again be overwhelmed if the U.K. variant spirals out of control. The U.K. variant has been identified in 467 people in 32 states, with Florida topping the list with at least 147, and California, at least 113.

The U.K. variant — known officially as B.1.1.7 — is expected to become the dominant variant within a matter of weeks; L.A. County officials announced the second confirmed case of the variant Saturday, which they say was "spreading in the county." At least two cases have been identified in San Bernardino County.
San Diego County has California's largest cluster of known cases of B.1.1.7 — at least 109 confirmed cases and 44 additional cases linked epidemiologically to known variant cases, officials said last week. Health authorities in San Diego County announced last week the first death linked to B.1.1.7, a 71-year-old man suspected to have been infected with the new strain, who was a household contact of someone who was confirmed to have been infected by the variant. Two people have been hospitalized with the variant.
The median age of those sickened with B.1.1.7 is 30, but the age range of those infected has been between newborn and age 77, said Dr. Wilma Wooten, the San Diego County health officer.
The growth of the B.1.1.7 variant "requires us to remain vigilant, to not be complacent, to continue to take all the necessary precautions to slow the spread," warned Nathan Fletcher, chair of the San Diego County Board of Supervisors.
The B.1.1.7 variant of the coronavirus led to a rapid expansion of disease across Britain, Portugal and Ireland, and quickly became the dominant strain in those countries, Natasha Martin, associate professor in the UC San Diego Division of Infectious Diseases and Global Health, told the Board of Supervisors last week.
"This particular variant is estimated to be 50% to 70% more transmissible than previous variants, leading to surges in cases," Martin said. "There is a recent evidence that it may lead to higher mortality as well."
California's first detection of the B.1.1.7 variant came Dec. 30 in San Diego County. It's now estimated to comprise 5% of circulating strains, Martin said.
"The question is not whether this strain will become dominant, but how long it will take, and what effect it will have on our epidemic trajectory, given its increased transmissibility," Martin said.
A big problem is that the growing dominance of B.1.1.7 could dramatically worsen the pandemic in California. Currently in California, the effective reproduction number — the average number of people to which a contagious person transmits the coronavirus — is around 0.8, meaning every infected person in California now transmits the virus to fewer than one person, which explains why the pandemic is improving now.
But should B.1.1.7 become the dominant strain, with a 50% to 70% increase in transmissibility, the reproduction number could become greater than 1, and could dramatically increase cases, Martin warned.
Scientific simulations suggest officials and the public need to operate with exceptional caution in reopening the economy, Martin said.
Even a decent vaccination plan is no match for the U.K. variant if people abandon mask wearing and physical distancing in the same way they did in the lead up to Thanksgiving, according to a simulation presented by Martin.
If people reject mask wearing and physical-distancing practices as they did in the autumn, San Diego County would likely see its current new coronavirus case rate — now about 1,500 new cases a day over a weekly period, the lowest in roughly two months — rise to as much as 7,000 new cases a day, beyond a level "which would overwhelm our health systems," Martin said.
That would be far worse than anything San Diego County has experienced so far in the pandemic. San Diego County topped out at about 3,600 new coronavirus cases a day for the seven-day period that ended Jan. 12.
“This scenario ... would overwhelm our health systems,” Martin said. "There is some emerging data that the B.1.1.7 [strain] is more lethal. So we could expect even more deaths than we're seeing now for every case."
Lowering the amount of circulating virus would delay the expansion of the B.1.1.7 variant, Martin said.
"I can't stress this enough — with the emergence of B.1.1.7 and other strains which may be more transmissible and potentially more lethal — now is the time to double down on reducing transmission and expanding vaccination," Martin said. "In the coming weeks, we need to urgently focus all efforts on reducing transmission, ensuring a robust vaccination response and approach reopening with caution."
The concern about the strain, as well as the ongoing high number of daily cases, led San Diego County's Wooten last week to keep in place a local order that prohibits restaurants from allowing outdoor restaurant dining between 10 p.m. and 5 a.m. San Francisco has also kept in place an order requiring dine-in customers to leave outdoor dining areas by 10 p.m.
That's a different stance from L.A. County, which on Friday allowed outdoor dining to not only resume again, but also during those late-night hours.
L.A. County Public Health Director Barbara Ferrer said Monday that the U.K. variant has not dominated in L.A. County so far. She urged people to keep being cautious — wear masks, continue physically distancing, and stay at home as much as possible — and, if dining at restaurants outdoors, to adhere to the new rules as much as possible.
They include dining at a table only with members of your household, with no more than six people and spaced at least eight feet away from other tables. Outdoor dining areas must have at least two noncontiguous sides that are completely open to increase the flow of breezes to dissipate exhaled virus particles, and guests are urged to wear masks when their servers approach.
"That's what we're trying to do right now: Keep the numbers as low as possible while we wait to get more vaccines and really accelerate the pace of vaccinations," Ferrer said.
Restaurants and other dining locations have been the source of the second-highest number of confirmed community outbreaks over the last 10 months, according to San Diego County data, comprising about 20% of identified outbreaks.
Wooten told the supervisors she was uncomfortable allowing restaurants to reopen for outdoor dining service late at night because restaurants that did so often transitioned into parties — a situation in which people are far more likely to mix with people from other households, breathe out their respiratory particles into other people's faces while talking, and dramatically increase the risk of a super-spreader incident because people drinking aren't wearing masks.
"I am uncomfortable with the number of cases that we still have with changing that particular order at this time," Wooten said.
© (San Diego County) Restaurants comprised the source of the second highest number of coronavirus outbreaks in San Diego County. (San Diego County)
Currently available vaccines are believed to be effective against the B.1.1.7 variant.
Officials have also voiced concern about the variant identified out of South Africa, known as B.1.351, and its closely related variant from Brazil, known as P.1. The South African variant has been detected in two cases in South Carolina — in different parts of the state and not believed to be epidemiologically linked — and one in Maryland. The Brazilian variant has been identified in a single case in Minnesota.
The South African variant has also caused concern because vaccines are less effective against the virus, although "it still was not below the cutoff where you would expect some degree of efficacy," said Dr. Anthony Fauci, the U.S. government's top infectious diseases expert.
Nonetheless, scientists and government officials are now working on an additional booster shot in case officials feel it's needed to protect against new strains.
"This is a wakeup call to all of us," Fauci told reporters during a briefing Friday. "We will continue to see the evolution of mutants. So that means we ... will have to be nimble to be able to adjust readily to make versions of the vaccine that actually are specifically directed towards whatever mutation is actually prevalent at any given time."
This is also all the more reason to ramp up vaccination efforts as quickly as we can. "Viruses cannot mutate if they don't replicate," Fauci said.
It's no coincidence that the rise of problematic mutations are occurring in nations where the coronavirus has run rampant. "Letting virus run wild, like [the U.S. and] Brazil did, endangers everyone," Dr. Ashish Jha, dean of the Brown University School of Public Health, tweeted.
The emergence of the U.K. strain could mean that the summertime — instead of being a quiet period for the coronavirus — could actually result in higher prevalence of the coronavirus than scientists would have otherwise expected, Dr. Scott Gottlieb, former commissioner of the U.S. Food and Drug Administration, told the CBS News program "Face the Nation" on Sunday.
"What's going to likely happen is that the prevalence is going to be high in certain regional hot spots. So we'll have hot spots of infection and maybe epidemics in parts of Florida, parts of Southern California, because of B.1.1.7. They'll never really get out of it, but the rest of the country will see prevalence come down," Gottlieb said.
One silver lining to the South African and Brazilian variants, though, is that — unlike the U.K. variant — they don't seem to be more transmissible than the mainstream variety of the virus, Gottlieb said. That means "we have time to get control of those variants and develop new boosters that could protect against them, vaccine boosters," Gottlieb said.
Michael Osterholm, director of the University of Minnesota's Center for Infectious Disease Research and Policy, offered a far more dire forecast than Gottlieb did in an interview Sunday on the NBC News program "Meet the Press." Osterholm suspected the U.K. variant's appearance is akin to watching a hurricane form, and forecasted a new surge in the next six to 14 weeks.
"And if we see that happen — which my 45 years in the trenches tells me we will — we are going to see something like we have not seen yet in this country," Osterholm said. "That hurricane's coming."
Paul Sisson of the San Diego Union-Tribune contributed to this report.
This story originally appeared in Los Angeles Times.

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