Why omicron subvariant BA.5 is an important issue

Why omicron subvariant BA.5 is an important issue

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(CNN) — Once again, covid-19 seems to be everywhere. If you feel that he took you by surprise, you are not the only one.

After the omicron tsunami that swept through the United States in January and the smaller increase in cases in the spring caused by the BA.2 subvariant, we might have thought it was possible to ignore the coronavirus for a while.

After all, the US Centers for Disease Control and Prevention (CDC) estimated in December that almost all Americans had been vaccinated or had antibodies from a previous infection. Surely all that immunity would give us a break.

But suddenly, many people who had recovered from Covid-19 in March or April found themselves exhausted, coughing and seeing two red lines on a rapid test. How can this happen again, and so soon?

The culprit this time is another descendant of omicron, the BA.5. He has three key mutations in his spike protein that make him better at infecting our cells and more adept at outwitting our immune defenses.

In just over two months, the BA.5 surpassed its predecessors to become the dominant cause of covid-19 in the United States. Last week, this subvariant caused nearly 2 out of 3 new Covid-19 infections in this country, according to the latest data from the CDC.

Laboratory studies of antibodies in the blood of people who have been vaccinated or have recovered from recent covid-19 infections have looked at how well they resist BA.5, and this subvariant is able to evade them. So people who got sick with covid as recently as winter or even spring may be vulnerable to the virus again.

“We don’t know about the clinical severity of BA.4 and BA.5 compared to our other omicron subvariants,” CDC Director Dr. Rochelle Walensky said at a Covid-19 Response Team briefing. at the White House on Tuesday. “But we do know that it is more transmissible and more evasive of immunity. People with a previous infection, even with BA.1 and BA.2, are probably still at risk of getting BA.4 or BA.5.”

New wave of covid-19 in the US with the BA.5 subvariant 2:05

A full wave

The result is that we are getting sick en masse. With Americans now more likely to take faster home tests, official case counts, currently hovering around 110,000 new infections a day, reflect only a fraction of the true burden of the disease.

“We estimate that for every reported case there are 7 unreported cases,” Ali Mokdad, professor of health metrics sciences at the University of Washington’s Institute for Health Metrics and Evaluation, wrote in an email.

Other experts believe the surge could be up to 10 times larger than what is now reported.

“We’re probably close to a million new cases a day,” Dr. Peter Hotez told CNN on Monday. “This is a full-blown BA.5 surge that we’re seeing this summer. It’s actually looking worse in the southern states, just like in 2020, just like in 2021,” said Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine in Houston.

That puts us in the range of cases reported during the first wave of the omicron variant, in January. Remember when it seemed like everyone got sick at the same time? That is the situation in America again.

That may not sound like much, because vaccines and better treatments have drastically reduced the risk of death from covid-19. Still, between 300 and 350 people die on average every day from covid-19, enough to fill a large passenger plane.

“This is unacceptable. It’s too high,” Dr. Ashish Jha, coordinator of the White House Covid-19 Response Team, said at Tuesday’s briefing.

Daily hospitalizations are also increasing in the United States. The fraction of patients needing intensive care has increased by 23% in the last two weeks. And other countries are also experiencing waves of BA.5s.

“I am concerned that Covid-19 cases will continue to rise, putting further pressure on stretched health systems and health workers. I am also concerned about the trend of rising deaths,” said Tedros Adhanom Ghebreyesus, Director General of the World Health Organization, at a press conference on Tuesday after the body’s decision to maintain its emergency declaration for covid-19.

The pandemic, he said, “is nowhere near over.”

What is at stake with the continuous spread

More treacherous health risks must also be taken into account. A recent study comparing the health of people who had been infected one or more times with COVID-19 found that the risk of new and sometimes long-lasting health problems increased with each subsequent infection, suggesting that reinfections are not necessarily benign. .

Although vaccination reduces the risk of contracting covid for a long time, a certain percentage of people have lasting symptoms after a reinfection.

That’s another reason why the high number of covid-19 cases is such a big deal: as the virus continues to spread rampantly, it has every opportunity to mutate into even fitter, more infectious versions of itself. . It does it faster than we can change our vaccines, which leaves us stuck in a process of infection and re-infection of covid.

On Tuesday, Dr. Anthony Fauci, director of the National Institutes of Allergy and Infectious Diseases, called on Americans to use every tool available to stop the spread of the virus, including wearing masks, ventilation and distancing.

“We have to keep virus levels as low as possible, and that’s our best defense. If a virus doesn’t replicate and spread very robustly, it has less chance of mutating, which gives it less chance of evolve into another variant,” Fauci said at a briefing.

In fact, this is already happening.

The subvariant BA.2.75 enters the scene

As the United States grapples with the BA.5 subvariant, variant hunters around the world are keeping a close eye on another omicron descendant, BA.2.75. It has been detected in about 10 countries, including the United States, and appears to be growing rapidly in India.

BA.2.75 has nine changes to its spicule that distinguish it from BA.2 and about 11 changes compared to BA.5, according to Tom Peacock, a virologist at Imperial College London.

Several of the BA.2.75 mutations are in a region of the spike protein that is known to be an important place for antibodies to bind to stop the virus, said Ulrich Elling, a scientist at the Austrian Academy of Sciences. that supervises the variants of coronavirus for that country.

There is little information to work with: it is not yet known, for example, how BA.2.75 may compete with BA.5 or whether it causes more severe disease. But experts say it has all the hallmarks of a variant that could go global.

“It’s already spread to many different countries, so we know it has some staying power,” said Shishi Luo, associate director for bioinformatics and infectious diseases at Helix Labs, which decodes virus samples for the CDC and other clients.

Because of that, and because of the changes in the region of the virus that our antibodies look for to inactivate it, “we know in advance that this one will cause some problems,” Luo said.

Based on what we know now, he expects this subvariant could drive a wave of COVID-19 in the fall in the United States.

In the meantime, Jha said, people should get whatever boosters they can to keep their immunity as strong as possible. US health officials stressed that people who get boosted now will be able to receive an updated vaccine this fall that includes the BA.4 and BA.5 strains.

Jha specifically urged Americans age 50 and older “if you haven’t gotten vaccinated this year, get vaccinated now. It could save your life,” he said.

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