The terrible horse race that is the US COVID-19 pandemic has been reduced to a competition between two tenacious strains of coronavirus: a variant native to California and an import from the United Kingdom.
New data from the Centers for Disease Control and Prevention indicates that the California strain was responsible for 13% of all coronavirus samples that were genetically sequenced as part of a new federal program in late February. An additional 7% of the samples were from the UK strain
Both versions of the virus worry scientists and health officials because they spread faster than their predecessors and appear to be less vulnerable to some of the drugs used to treat COVID-19. The California strain also showed signs of resistance to the current crop of COVID-19 vaccines.
In fact, studies have found that it is 20% more transmissible than other variants in wide circulation. Its enhanced transmission powers, its ability to short-circuit the effectiveness of treatments and its ability to compromise the effects of the vaccine prompted the CDC this week to declare the locally grown strain as a “variant of concern”.
Known to scientists as B.1.427 / B.1.429, it exploded in California during the fall and early winter, as the state struggled against a deadly increase in public holidays. It now predominates in his home state and in two of his neighbors. In mid-February, it accounted for 52% of California’s sequenced samples, 41% of Nevada’s samples and 25% of Arizona’s samples, CDC data show.
But the tension in the UK is giving your money a chance – with a projected impact ranging from uncertain to deeply worrying.
In January, researchers at the CDC predicted that the UK variant would become dominant in the United States in March. Epidemiologist Summer Galloway, the lead author of this report, said Wednesday that it is probably responsible for 20% to 30% of the samples being sequenced today.
The CDC does not have an equivalent estimate of how widespread the California variant is, Galloway said.
What the genetic sequencing data shows is that the UK variant, known as B.1.1.7, is making inroads across the country and has fueled a handful of local outbreaks. Its documented presence grew from 76 cases in 12 states in early January to 4,686 cases in all 50 states and in the District of Columbia in late February.
Variant B.1.1.7 is believed to be 50% more transmissible than other widely circulated variants, and a study published this week in the journal Nature suggests that it is 61% more likely to cause serious illness or death.
The prospect that this could lead to yet another wave of infections in the United States has helped spur a determined effort to expand vaccinations.
At the same time, however, many state governors are easing restrictions on wearing masks, dining in restaurants and attending large gatherings.
The CDC’s new findings prompted Dr. Eric Topol, director of the Scripps Research Translational Institute in La Jolla, to declare that the California variant “is becoming obsolete”.
The fact that the transmission rate of the UK variant is higher than that of the California strain means that it “will be quickly eliminated by B.1.1.7,” he said. In a competition for dominance of the population, “dissemination rules the roost”.
Topol said that two other variants – one identified in South Africa (called B.1.351) and another in Brazil (P.1) are likely to have the same fate “because they do not carry the improved propagation capacity like B.1.1.7. “
Galloway said that neither the South African nor the Brazilian variant gained much space in the United States. Although both are also called “worrying variants”, neither has been responsible for more than 0.05% of genetically analyzed coronavirus infections in the country since January.
But in Minnesota, Michigan and Florida, sudden outbreaks of new cases involving the UK variant have posed new challenges for public health officials struggling to end the pandemic with aggressive vaccination campaigns. These outbreaks suggest that estimates of the highest transmissibility of B.1.1.7 have not been overstated.
In Ionia, Michigan, the variant was at the center of a major outbreak at the Bellamy Creek Correctional Center, where 1,600 prisoners are incarcerated.
On February 9, state officials acknowledged an outbreak in which 80 prisoners appear to have been infected by a single official. On Wednesday, even after the facility adopted an extensive testing program, personal protective equipment and movement limitations, the number of infected people increased to 425 prisoners and 26 employees, said Chris Gautz, spokesman for the Department of Corrections of Michigan.
They were all infected with the UK variant, Gautz said.
In Minnesota, an outbreak involving the UK variant disrupted virtually all youth sports in Carver County and put the state at risk by reopening in a series of activities.
On January 9, the state recorded five cases in its southwest corner. Just over two months later, the state found more than 250 cases in more than two dozen counties across the state. Carver County recorded an overall weekly case growth of 80% from February to March.
In addition to being more contagious, the strain was also associated with higher mortality, “particularly among older adults and people with underlying diseases,” said Dr. Ruth Lynfield, state epidemiologist and medical director of the Minnesota Department of Health.
Minnesota’s experience with variant B.1.1.7 also raised concerns about another of its attributes: its apparent ability to spread and sicken children and young adults more readily than other strains. In Minnesota, a third of new cases have been seen in people under the age of 20.
This pattern has been documented by scientists elsewhere, but it has attracted less attention.
“What we saw really fits that image of being very contagious,” said Lynfield. “We were seeing this among young athletes and schools. And when we look at the teams, he really had that high attack rate. “