The stunning spread of BA.5 is creating a dangerous wave of COVID in California

As California suffers from another intense wave of coronavirus, the stunning proliferation of the BA.5 subvariant is becoming increasingly the focus of scientific scrutiny, with experts saying it could replicate much more efficiently than earlier versions of Omicron.

Compared to its ancestors, Omicron’s latest subvariant, BA.5, may have an increased ability to create large numbers of copies of the coronavirus once it enters human cells, a possible contributing factor for which the wave of Omicron this summer has been problematic.

By far the dominant version of the coronavirus circulating nationwide – accounting for around 65% of new cases in the week-long period ending Saturday, according to the US Centers for Disease Control and Prevention – BA .5 arguably combines aspects of last summer’s Delta variant with older versions of the highly contagious Omicron family, said Dr. Eric Topol, director of the Scripps Research Translational Institute in La Jolla.

“You may recall the term ‘Deltacron’ being used prematurely several months ago during the pandemic. But the ability to infect cells for BA.5 is closer to Delta than to the previous Omicron family of variants,” Topol wrote in a blog post.

In many ways, this wave of the pandemic felt different from other waves of Omicron earlier this year. Health experts say the behavior of the ultra-contagious strain shows the need for careful precautions.

Citing a preprint report out of Australia, Topol referenced lab study data that suggested BA.5 produced significantly more copies of the coronavirus compared to an earlier Omicron subvariant, BA. 2.

“There are more copies of the virus because BA.5 has a much better ability to enter cells…which may help explain why this version of the virus has caused a lot of problems, more than the other BA.5 subvariants. ‘Omicron,’ Topol wrote in his post. .

If BA.5 maintains its position as the main dominant variant for some time, it could eventually stabilize the situation in California and possibly indicate a situation where there will finally be a drop in cases, said Dr. Peter Chin-Hong, an infectious -disease expert at UC San Francisco.

But a possible key to this scenario is the emergence of another Omicron sub-variant, BA.2.75, which has caused concern in India.

“And I know, it’s super discouraging,” Chin-Hong said. Still, he said, there are ways to live life while taking steps to reduce risk.

Common steps public health officials recommend include staying up to date on vaccinations and boosters, getting tested before attending gatherings or events, and wearing masks in indoor or public places. crowded.

Separately, BA.5 appears to duplicate Omicron’s earlier traits of “immune evasion”, the ability of the virus to evade the human body’s immune response induced by vaccinations or previous infection.

From early March to early May, California reported about 2,300 weekly reinfections. From mid-May to mid-June, the state reported about 10,400 weekly reinfections — around the time BA.5 and another closely related subvariant, BA.4, began circulating widely.

Omicron’s first subvariant, BA.1, which spread rapidly in the United States after Thanksgiving, already had dozens of mutations that made it harder for our immune system to recognize.

“So what’s happened now is, along with BA.5, it’s superimposed mutations on BA.1 that make it even more difficult for our immune system to recognize it,” Topol said.

Initial data from the Australian study suggesting reduced efficacy of Evusheld, a monoclonal antibody, against BA.5 was also troubling.

“So that’s another hallmark of immune evasion is that our monoclonal antibodies don’t work as well,” Topol said.

The question of whether BA.5 causes more severe disease in humans has not been settled.

Data from South Africa suggests BA.5 did not alter the risk of hospitalization compared with earlier versions of Omicron, Chin-Hong said.

Coronavirus case rates have remained at consistently high levels across the state for months, infecting significant numbers of people and hampering business operations. More and more coronavirus positive patients are seen in hospital.

In the week-long period ending Thursday, California averaged more than 15,500 new coronavirus cases per day. Per capita, this represents approximately 278 cases per week per 100,000 inhabitants. That’s down about 12% from the previous week, but officials and experts say the apparent drop could partly be the result of data outages over the July 4 holiday weekend. .

Los Angeles County’s rate of coronavirus cases has been relatively stable over the past week but remains high, at around 5,400 cases per day. Per capita, this represents 373 cases of coronavirus per week per 100,000 inhabitants.

Official counts are almost certainly a major undercount due to the widespread use of home tests – the results of which are not reliably reported.

Statewide, 4,227 coronavirus-positive patients were hospitalized Monday, the highest one-day total since late February. In Los Angeles County, the latest patient count was 1,153, a 54% increase from two weeks prior.

Although a significant portion of these patients are not hospitalized due to complications from COVID-19 and may have tested positive after seeking care for another reason, officials say they are nonetheless exercising a particular strain on resources due to additional services needed to keep them from spreading the virus.

And as long as transmission remains high, health systems are unlikely to experience major relief.

“With more cases, we are obviously seeing more people in need of medical attention – and not just in our hospitals, but also in our emergency departments and urgent care centers which are full of many people in need of care for their COVID-related illness,” LA County Public Health Director Barbara Ferrer said during a recent briefing.

COVID-19 deaths are also starting to rise in LA County, from around 50 per week in early June to nearly 100 deaths per week now. At the height of Omicron’s winter surge, LA County reported more than 500 deaths per week.

In previous outbreaks, dominant strains like Delta last summer or Alpha previously remained for relatively long periods of time and were not quickly displaced by their successors, meaning an infected person could benefit from a high degree of protection for perhaps several months.

This delay has shortened considerably in the Omicron region. Since April, three different subvariants – BA.2, BA.2.12.1 and now BA.5 – have been estimated to be the dominant strain nationwide. This rapid succession means that it is possible for someone to be infected with an earlier edition of Omicron and then be re-infected with a later version several weeks later.

“Many people who are recently infected can probably get the virus, again, in three or four weeks, compared to the old days, where they have a three-month window period” when reinfection is less likely, said Chin Hong.

Chin-Hong said he knows people who, after getting infected, thought it gave them a pass to “go out even more and not worry so much,” only to end up with repeat infections. “That line of thinking isn’t great when you have the changing of the guard” of Omicron’s sub-variants, he added.

While some people remain asymptomatic or have mild symptoms, others report severe discomfort including high fever, raging sore throat and brain fog and fatigue that can last for weeks – or maybe be the onset of a long COVID, in which symptoms of illness may persist for months or years.

It is also likely that some people who have so far avoided becoming infected are no longer using certain protective measures they used to apply or are being exposed to family members and friends who have relaxed their protective practices. protection.

People “take more risks; they’re moving; they travel,” Chin-Hong said. Even in San Francisco, a number of people aren’t wearing a mask in places where it was once ubiquitous, meaning there’s less peer pressure to wear a mask in areas where it was once common, Chin-Hong said.

These measures remain largely voluntary at this point in many public places, but recent increases in positive coronavirus hospitalizations have brought LA ​​County closer to the possibility of issuing a new mask mandate that would apply to indoor public places. The county already requires mask-wearing on public transit and at airports, health care facilities and nursing homes, as well as on construction sites where there have been three or more coronavirus cases in a two-week period. .

If current trends continue, LA County could move from the average COVID-19 community level – which is defined by the United States Centers for Disease Control and Prevention and case and hospitalization rate factors – to the level raised on Thursday.

If the county is at the high community level of COVID-19 for the next three consecutive Thursdays, health officials are prepared to implement a new universal mask mandate in indoor public places for ages 2 and older starting on July 29.

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