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- Covid XBB.1.16: Symptoms of Covid variant Arcturus to know Hindustan Times
- What to know about Arcturus, a new coronavirus subvariant the WHO is tracking Detroit News
- ‘Arcturus,’ a COVID variant sweeping India, is now in the U.S., the CDC says—and it’s coming in hot. What it means for the future of the pandemic Yahoo Finance
- Why the world is unprepared if new Covid variant Arcturus proves deadly – in graphs The Independent
- View Full Coverage on Google News
Tag Archives: transmissible
XBB.1.5 may be ‘most transmissible subvariant of Omicron to date,’ scientists warn
CNN
—
Health experts voiced concern Wednesday over the rapid growth of the new Omicron sublineage XBB.1.5, advising the public to stay informed but not alarmed as they work to learn more.
Over the month of December, the percentage of new Covid-19 infections in the United States caused by XBB.1.5 rose from an estimated 4% to 41%.
“That’s a stunning increase,” Dr. Ashish Jha, the White House Covid-19 response coordinator, wrote in a Twitter thread.
Officials at the World Health Organization shared similar thoughts Wednesday.
“We are concerned about its growth advantage,” said Maria Van Kerkhove, an epidemiologist who is the WHO’s technical lead on Covid-19.
Van Kerkhove noted that XBB.1.5, which was first detected in the United States, has spread to at least 29 countries and “is the most transmissible form of Omicron to date.”
“We do expect further waves of infection around the world, but that doesn’t have to translate into further waves of death because our countermeasures continue to work,” she said.
Jha noted that effective tools to avoid severe Covid-19 infections include rapid tests, high-quality masks, ventilation and filtration of indoor air, oral antiviral pills and updated vaccines.
“We will soon have more data on how well vaccines neutralize XBB.1.5,” Jha said, suggesting that research to determine vaccine effectiveness against the new sublineage is underway.
Jha said XBB.1.5 is probably more able to slip past our immune defenses and may be more contagious. But he said it’s still not clear whether it causes more severe disease, something that was also stressed by Van Kerkhove.
She said WHO is working on a risk assessment for this sublineage and hopes to publish it within the next few days. The group’s technical advisers are looking at both real-world data on hospitalizations and lab studies to assess severity.
Jha said that although he is concerned about XBB.1.5, he doesn’t think it represents a huge setback in the fight against Covid-19.
“And if we all do our part,” he wrote, “We can reduce the impact it will have on our lives.”
New study finds omicron no less severe than earlier variants, and not just more transmissible
A new study conducted by researchers at Harvard Medical School among others has found that the omicron variant of the coronavirus that causes COVID-19 is just as severe as earlier variants, and not more transmissible but no less severe, as previously thought.
The study was based on the records of 130,000 COVID patients in Massachusetts and carried out by researchers at Massachusetts General Hospital and Minerva University along with Harvard and is currently being peer-reviewed by Nature Portfolio, according to a Reuters report.
But its findings, which evaluated the severity of omicron after accounting for the effect of vaccines, underscores how important vaccines and boosters are, and shows they helped rein in hospitalizations and deaths during the omicron surge.
“Although the unadjusted rates of hospital admission and mortality appeared to be higher in previous waves compared to the Omicron period, after adjusting for confounders including various demographics, Charlson comorbidity index scores, and vaccination status (and holding the healthcare utilization constant), we found that the risks of hospitalization and mortality were nearly identical between periods,” the authors wrote.
“Our analysis suggests that the intrinsic severity of the Omicron variant may be as severe as previous variants.”
The study comes after a Washington Post analysis of Centers for Disease Control and Prevention data earlier this week found that omicron caused a spike in deaths in January and February among people who were vaccinated. Those deaths were mostly among elderly people and those with compromised immune systems and are thought to have had waning protection from vaccination.
See now: Omicron caused spike in deaths in vaccinated people, analysis finds, though unvaccinated remain most at risk
Experts agree that vaccination and boosters remain the best protection against severe disease and death and continue to urge unvaccinated people to get their shots. And there are concerns that the initial view that omicron caused only mild symptoms may have actually persuaded the vaccine hesitant that they didn’t need to be inoculated.
The study comes as cases continue to rise across the U.S. after their steep decline early in the year, driven by the BA.2 variant of omicron, and two subvariants that appear to be even more infectious. The two, named BA.2.12 and BA.2.12.1, were highlighted by health officials in New York state recently.
The U.S. is averaging 67,953 cases a day, up 59% from two weeks ago, according to a New York Times tracker. Cases are climbing in all but four states and territories and have more than doubled from two weeks ago in more than a dozen, the tracker shows.
The country is averaging 18,181 hospitalizations a day, up 20% from two weeks ago, but still relatively low. The daily death toll has fallen below 400 to 366 on average.
The World Health Organization said Thursday that new estimates show that the full death toll associated either directly or indirectly with the COVID-19 pandemic between Jan. 1, 2020, and Dec. 31, 2021, is about 15 million.
That number compares with the tally provided by Johns Hopkins University of 6.24 million.
Coronavirus Update: MarketWatch’s daily roundup has been curating and reporting all the latest developments every weekday since the coronavirus pandemic began
Other COVID-19 news you should know about:
• U.S. regulators on Thursday strictly limited who can receive Johnson & Johnson’s COVID-19 vaccine due to a rare but serious risk of blood clots, the Associated Press reported. The Food and Drug Administration said the shot should only be given to adults who cannot receive a different vaccine or specifically request the Janssen vaccine from J&J
JNJ,
-0.83%.
U.S. authorities for months have recommended that Americans starting their COVID-19 vaccinations use the Pfizer
PFE,
+0.98%
or Moderna
MRNA,
-5.89%
shots instead. FDA’s vaccine chief, Dr. Peter Marks, said the agency decided to restrict the vaccine after taking another look at the data on the risks of life-threatening blood clots and concluding that they are limited to J&J’s vaccine.
• North Carolina state employees will get an extra day of vacation for receiving a COVID-19 booster, Gov. Roy Cooper announced as the state government there uses a new incentive to increase vaccination rates, the AP reported separately. Cooper signed an executive order that provides the leave to permanent, probationary or time-limited workers whose cabinet-level agencies report to him. The extra time off will be given to those who have already received the first COVID-19 booster or those who show documentation by Aug. 31 of receiving one.
• The number of unruly air-passenger incidents in the U.S. has fallen since a federal judge in Florida overturned the federal mandate, the New York Times reported, citing data from the Federal Aviation Administration. The agency reported 1.9 incidents per 10,000 flights during the week ending April 24, down from 4.4 incidents per 10,000 flights a week earlier. It declined to cite a reason for the drop. The CDC continues to recommend that people wear face masks on public transport and in public-transport hubs, especially as subvariants of omicron continue to circulate.
• China’s elderly population’s reluctance to get vaccinated is challenging the country’s zero-COVID strategy, the Washington Post reported. Unlike most of China’s coronavirus prevention measures, vaccination is not mandatory, and low uptake among the country’s most vulnerable groups is a major reason Communist Party leaders feel compelled to persist with a grueling “zero-COVID” approach. That has led to a strict lockdown in Shanghai that is now being eased. Chinese President Xi Jinping said relaxation of the strategy now would lead to “massive numbers of infections” and deaths.
Here’s what the numbers say
The global tally of confirmed cases of COVID-19 topped 516.2 million on Wednesday, while the death toll rose above 6.24 million, according to data aggregated by Johns Hopkins University.
The U.S. leads the world with 81.7 million cases and 996,996 fatalities.
The Centers for Disease Control and Prevention’s tracker shows that 219.9 million people living in the U.S. are fully vaccinated, equal to 66.3% of the total population. But just 101 million are boosted, equal to 45.9% of the vaccinated population.
New Mutant XE Omicron Variant May Be Most Transmissible Covid Yet – Deadline
The CDC announced this week that the BA.2 Omicron variant, which is reportedly 30% more transmissible than the original BA.1 Omicron strain — has become dominant among new cases sequenced in the United States. That’s a startling rise for a variant that was less than 1% of all sequences as recently as January. But, just as Americans are hearing about BA.2, there’s already a newer, even more transmissible variant on the rise.
There are actually three new variants that have been given designations. According to a recently-released report from the UK Health Services Agency, the two being called XD and XF are combinations of Delta and BA.1, or so-called “Deltacron” strains, which have been talked about for months but made no significant inroads in any country.
XD is present in several European countries, but has not been detected in the UK, according to the report. XF caused a small cluster in the UK but has not been detected there since February 15. The variant of greater concern, it seems, is the one dubbed XE.
Like the other two new arrivals, XE is a recombinant strain, meaning it is made up of two previously-distinct variants. But it is not a Deltacron mix. XE is actually made up of the original Omicron (BA.1) and the newer Omicron (BA.2) which has taken over in the U.S.
The World Health Organization issued a report yesterday with some preliminary findings.
“The XE recombinant was first detected in the United Kingdom on 19 January and >600 sequences have been reported and confirmed since,” reads the WHO document. “Early-day estimates indicate a community growth rate advantage of ~10% as compared to BA.2, however this finding requires further confirmation.”
Further confirmation is getting more difficult by the day, according to WHO, which registered concern this week at what it calls “the recent significant reduction in SARS-CoV-2 testing by several Member States. Data are becoming progressively less representative, less timely, and less robust. This inhibits our collective ability to track where the virus is, how it is spreading and how it is evolving: information and analyses that remain critical to effectively end the acute phase of the pandemic.”
Last week’s briefing from the UK Health Services Agency reinforces some of the WHO report’s assertions and urges caution about jumping to conclusions. One difference between the two documents is that the WHO data and analysis seems to be more recent.
From the UK HSA briefing:
XE shows evidence of community transmission within England, although it is currently less >1% of total sequenced cases. Early growth rates for XE were not significantly different from BA.2, but using the most recent data up to 16 March 2022, XE has a growth rate 9.8% above that of BA.2. As this estimate has not remained consistent as new data have been added, it cannot yet be interpreted as an estimate of growth advantage for the recombinant. Numbers were too small for the XE recombinant to be analysed by region.
To be clear, XE only accounts for a tiny fraction of cases worldwide. That may change, given that XE is thought to be about 10% more transmissible than the already more-transmissible BA.2. That means it may be roughly 43% more transmissible than the original Omicron that savaged the globe last winter.
But a new wave of infections from the now-dominant BA.2 has not materialized, even as restrictions have been eased. So hopefully the trend with XE, should it out-compete BA.2, will be similar. Only time — and good surveillance — will tell.
Omicron BA.2 Variant Now Dominant In U.S.; More Transmissible Strain – Deadline
The more transmissible strain of Omicron, BA.2, is now the dominant Covid variant in the United States. In just the last week, it has risen from 35% of all new cases genetically sequenced to 55%, per CDC data. That’s a remarkable 80% jump in just seven days.
In the swath of the Northeast that includes Pennsylvania, New York, New Jersey, Vermont, New Hampshire, Connecticut, Massachusetts, Rhode Island and Maine and has a population of about 55 million people, BA.2 now accounts for more than 70% of all new cases. That’s up from just over 50% the week before and 38% the week before that.
CDC
A late January report from the Statens Serum Institut, which operates under the auspices of the Danish Ministry of Health, found that “BA.2 may be approx. 30% more transmissible than BA.1 (the original Omicron).” Some analyses since then have claimed the variant’s transmissibility advantage is even higher.
The good news is that the Omicron strains are much less virulent than Delta, but as the U.S. saw in early February of this year, Omicron’s increased transmissibility can still create a wave of deaths equal to or surpassing that of Delta by the sheer number of infections alone.
So far, that is not happening, with only minor jumps in the number of cases reported in parts of the Northeast and no significant jumps in hospitalizations.
One state where cases have risen alongside BA.2 is Florida. Covid numbers from data hub Helix.com indicate that, by mid-March, Omicron BA.2 accounted for 66% of all new cases in the state. The 7-day average of new cases in the state have risen from about 2300 on March 23 to about 4200 on March 28, per CDC data. But hospitalizations have actually dropped, so whether or not BA.2 will have a substantial impact on the local healthcare system remains to be seen, as hospitalizations generally lag cases by 2 weeks.
New omicron variant BA.2 is 30% more transmissible. Should you be worried?
New studies of the BA.2 sub-variant of the omicron strain of COVID — known as “stealth” omicron — show that the lineage is more transmissible than the original omicron, but may not be more severe. And so far, it doesn’t seem to be provoking another surge in cases.
While experts are keeping a close eye on BA.2 as it circulates around the world — it is already in all 50 U.S. states — many aren’t worried that it will upend recent progress in winding down the pandemic.
Here’s what you need to know.
What is BA.2?
BA.2 is a sub-variant of the omicron variant of COVID-19. It’s known as “stealth” omicron not because it’s harder to detect on coronavirus tests, said Dr. Peter Chin-Hong, an infectious disease expert at UCSF, but because it is not always recognized as omicron.
BA.2 lacks the specific genetic feature that allows scientists to quickly identify a COVID-19 strain as omicron when sequencing, which means BA.2 can look like delta in initial screening.
The test will show “positive” for COVID, Chin-Hong explained, but not that it’s omicron.
Because BA.2 is a subvariant of omicron, the California Public Health Dept. does not track it separately, the agency said.
Is BA.2 more infectious than omicron?
Studies estimate that BA.2 is about 30% more transmissible than the original BA.1 omicron version, though that difference in contagiousness isn’t as large as the leap between delta and omicron, the WHO said. On Thursday, South Africa’s top public health body said that while its data show BA.2 does appear to be more infectious than BA.1, it does not cause more severe disease, Reuters reported.
Will BA.2 cause another surge in cases?
While the growth of BA.2 is now outpacing that of BA.1, the World Health Organization nevertheless notes that “the global circulation of all variants is reportedly declining,” meaning that BA.2 does not appear to be spurring renewed outbreaks.
Chin-Hong said that, while it is important to keep an eye on the strain’s spread, highly vaccinated places that have already seen large omicron surges, like the Bay Area, are likely not going to see huge spikes fueled by BA.2.
Still, he said, the omicron sub-variant is very likely to infect people who are not vaccinated and have not had omicron, he said, which could “slow the sense of normalcy” for some.
He also noted that because BA.2 is arising just when many places are dropping mask mandates and other restrictions, it’s hard to know whether increased cases are because of the sublineage or just a natural consequence of the lowered restrictions.
“It’s hard to see what effect there is because of BA.2 specifically,” he said.
Is it BA.2 more severe?
While there are some mixed results in studies, real world data so far show that BA.2 is not causing more severe disease than the original omicron.
A Japanese study on lab mice has found that the sub-variant could potentially cause more severe disease than its parent omicron — but that phenomenon has not played out in humans. The study’s results “look scary,” Chin-Hong said, but doesn’t necessarily translate to humans in large part because “it doesn’t account for previous immunity.”
Chin-Hong added that he is not expecting more people to be hospitalized with BA.2 than with BA.1, especially since vaccines continue to effectively protect against severe disease, hospitalization and death.
However, he also noted that even though omicron and BA.2 are mild for many, UCSF hospital has continued to treat patients with serious illness, most of them unvaccinated.
“The vaccine is still the best protection,” he said.
Can BA.2 reinfect people who’ve already had COVID-19?
Like the original strain of omicron, BA.2 can reinfect people who’ve had COVID before, but it doesn’t appear to be able to reinfect people who’ve already had omicron, especially those who are vaccinated, Chin-Hong said.
A study out of Denmark found that, while BA.2 was able to reinfect a small number of people who already had the original omicron, those were “young unvaccinated individuals with mild disease not resulting in hospitalization or death.”
Chin-Hong added that people who are unvaccinated and had a mild case of omicron may not have produced a robust enough immune response to fight off another infection from BA.2, since mild infections don’t “wake up” as many T cells and B cells — “yet another reason to get vaccinated,” he said.
WHO also said that initial data from real-world infections “suggest that infection with BA.1 provides strong protection against reinfection with BA.2, at least for the limited period for which data are available.”
What does BA.2 mean for the future of the pandemic?
BA.2 is another twist from an unpredictable virus, and researchers and scientists are staying vigilant.
Chin-Hong said that while he isn’t terribly worried about BA.2 itself, people who are unvaccinated and haven’t gotten omicron are very likely to get BA.2 he said, and that opportunity for increased transmission worries him.
“Every time you have a transmission, you can have a mutation,” he said. “The spawn of BA.2 will be something different, but we don’t know what. And there’s no guarantee that it will still be mild.”
“At this point the most worrisome thing about BA.2 is that it demonstrates that it’s possible for a variant to be more infectious than Omicron,” Dr. Bob Wachter, chair of medicine at UCSF, wrote on Twitter. “There’s no guarantee that a future variant won’t be more immune-evasive and/or severe. But luckily, not this one.”
Danielle Echeverria is a San Francisco Chronicle staff writer. Email: danielle.echeverria@sfchronicle.com Twitter: @DanielleEchev
Omicron could be the most transmissible Covid variant we get: experts
It’s too soon to know if Covid’s omicron variant will hasten the end of the nearly two-year-long Covid-19 pandemic. But some experts say that when it comes to contagiousness, omicron could be the “most transmissible the virus can get.”
The reason: Due to “evolutionary constraints” on how many mutations and changes the virus can make, omicron could be “the ultimate version of this virus,” Dr. William Moss, executive director of the International Vaccine Access Center at the Johns Hopkins Bloomberg School of Public Health, tells CNBC Make It.
Studies show that omicron is more than four times as transmissible as Covid’s delta variant, and that it evades immunity better than delta. As long as the virus keeps spreading, Moss says, it’ll continue to mutate going forward, creating more variants down the road.
But those mutations will probably be like “sons of omicron,” he says — not so different that the virus can escape immunity from vaccines or previous omicron infections.
For Covid to stop spreading, a significant portion of a population needs to maintain some level of simultaneous immunity — a challenge, since so-called “natural immunity” provides inconsistent levels of protection for unpredictable amounts of time. It’s estimated that 94% of the population must carry some form of immunity to interrupt the chain of transmission, according to the Mayo Clinic.
Moss’ theory is “my own kind of gut feeling, and I know other people don’t agree with this,” he admits.
Other experts say his theory could be accurate, but it’s simply too soon to tell.
“By the looks and behavior, my guess is for SARS-CoV-2, this is probably as high as it will/need climb” in terms of transmissibility, says Dr. T. Jacob John, a retired professor and head of departments of clinical virology and microbiology at CMC Vellore. But it’s a waiting game to see if omicron will displace delta as fully as delta displaced variants like alpha, beta, and gamma, John says.
That matters: “If delta is replaced, then omicron has no ‘biological need’ to increase transmission efficiency,” John says.
An early study from South Africa released in late December suggests that it’s possible, citing patients who were found to have extra immunity against delta after recovering from omicron infections. But John says the scenario is unlikely. Instead, he suspects that both variants could stick around long enough to circulate as endemic viruses going forward.
“[F]uture mutations may be based on them,” he says.
For Dr. David Ho, a world-renowned virologist and Columbia University professor, any prediction of Covid’s future requires a healthy amount of caution. Covid “has surprised us every few months,” he says.
Ho’s metaphor to prove his point: When famed American sprinter Carl Lewis ran the 100-meter dash, “he was so impressive that it was hard to imagine anyone running faster. Then came Usain Bolt.”
In other words, Ho says, predicting whether the pandemic’s severity will peak with omicron is a challenge. “I agree there has to be a limit,” he says. “But has that been reached by omicron?”
Dr. Bruce Farber, chief of infectious diseases at New Hyde Park, New York-based hospital network Northwell Health, agrees: While omicron is extraordinarily contagious, he says, the virus’ future remains uncertain.
“This virus has taken so many unprecedented turns. I would be reluctant to conclude that it is the ultimate variant at this time,” Farber says.
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Omicron could burn through the U.S. — and potentially hasten the Covid pandemic’s end, says expert
Study: Omicron could be more transmissible due to sharing genetic material with common cold
The omicron variant may have evolved from the virus associated with the common cold, researchers out of Cambridge, Mass., said in a preliminary study released Friday, which suggests the variant could be much more transmissible than previously thought.
Nference, a biomedical company, released data revealing that omicron shares similar genetic material to HCoV-229E, a human coronavirus that causes common cold symptoms. Researchers posit that omicron evolved from an individual who was “co-infected” with Sars-CoV-2 and HCoV-229E.
The authors of the study found both viruses inside gastrointestinal and respiratory tissues of infected individuals. They wrote that “genomic interplay,” or the exchange of genetic material, could have led to omicron’s emergence. No other Sars-coV-2 variants have similar cross-genetic material with HCoV-229E.
Nference also compared omicron’s genetic material to other Sars-CoV-2 variants, including the highly transmissible and dominant delta variant. They found omicron hosts 26 mutations distinct to the variant.
Omicron first appeared in South Africa on Nov. 24 before it spread to more than two dozen countries on six continents, including the U.S., in roughly a week.
The variant has not yet been declared more deadly or more transmissible by the World Health Organization or the Centers for Disease Control and Prevention, but its spread — much faster than delta — has alarmed the world and public health experts. The U.S. is among a number of countries restricting travel from multiple southern African countries.
South Africa, which had seen a lull before omicron was detected, saw cases jump from roughly 2,000 daily on Thanksgiving to more than 11,000 daily on Thursday.
Anthony FauciAnthony FauciThree omicron cases of COVID-19 identified in Maryland: Gov. Hogan FDA eyes rapid review for omicron vaccines, drugs: report Fauci calls out Fox News for letting host compare him to Nazi doctor: ‘Astounded’ MORE, the director of the National Institute of Allergy and Infectious Diseases, said during a press conference on Wednesday that omicron’s deadliness and transmissibility, as well as the ability of vaccines to combat it, are still unclear.
“We’re going to get that information,” he added. “We’re going to get a lot more information.”
Is Omicron More Contagious Than Delta? A Virus Expert Explains What We Know So Far
A new variant named Omicron (B.1.1.529) was reported by researchers in South Africa on Nov. 24, 2021, and designated a “variant of concern” by the World Health Organization two days later. Omicron is very unusual in that it is by far the most heavily mutated variant yet of SARS-CoV-2, the virus that causes COVID-19.
The Omicron variant has 50 mutations overall, with 32 mutations on the spike protein alone. The spike protein – which forms protruding knobs on the outside of the SARS-CoV-2 virus – helps the virus adhere to cells so that it can gain entry. It is also the protein that all three vaccines currently available in the US use to induce protective antibodies.
For comparison, the Delta variant has nine mutations. The larger number of mutations in the Omicron variant may mean that it could be more transmissible and/or better at evading immune protection – a prospect that is very concerning.
I am a virologist who studies emerging and zoonotic viruses to better understand how new epidemic or pandemic viruses emerge. My research group has been studying various aspects of the COVID-19 virus, including its spillover into animals.
Why do new SARS-CoV-2 variants continue to emerge?
While the unusually high number of mutations in the Omicron variant is surprising, the emergence of yet another SARS-CoV-2 variant is not unexpected.
Through natural selection, random mutations accumulate in any virus. This process is sped up in RNA viruses, including SARS-CoV-2. If and when a set of mutations provides a survival advantage to a variant over its predecessors, the variant will out-compete all other existing virus variants.
Does the Omicron variant’s greater number of mutations mean it is more dangerous and transmissible than Delta? We simply don’t know yet. The conditions that led to the emergence of the variant are not yet clear, but what is clear is that the shear number and configuration of mutations in Omicron is unusual.
One possible explanation for how viral variants with multiple mutations emerge is through prolonged infection in a patient whose immune system is suppressed – a situation that can lead to rapid viral evolution.
Researchers have hypothesized that some of the earlier SARS-CoV-2 variants, such as the Alpha variant, may have stemmed from a persistently infected patient. However, the unusual constellation and numerous mutations in the Omicron variant make it very different from all other SARS-CoV-2 strains, which raises questions about how it came about.
Another possible source of variants could be through animal hosts. The virus that causes COVID-19 can infect several animal species, including mink, tigers, lions, cats, and dogs.
In a study that is not yet peer-reviewed, an international team that I lead recently reported widespread infection by SARS-CoV-2 in free-living and captive white-tailed deer in the US. Therefore, we also cannot rule out the possibility that the Omicron variant emerged in an animal host through rapid evolution.
How the Delta variant became dominant worldwide
Delta is between 40 and 60 percent more transmissible than the Alpha variant and nearly twice as transmissible as the original SARS-CoV-2 virus first identified in China. The Delta variant’s heightened transmissibility is the primary reason why researchers believe it was able to out-compete other variants to become the dominant strain.
A key factor in viral fitness is its replication rate – or how quickly a virus can make more copies of itself. The Delta variant replicates faster than previous SARS-CoV-2 variants, and a not-yet-peer-reviewed study estimated that it produces 1,000 times more virus particles than its predecessors.
In addition, people infected with the Delta variant are making and shedding more virus, which is another potential mechanism for its increased ability to spread.
Research suggests that a possible explanation for the Delta variant’s heightened ability to replicate is that mutations in the spike protein led to more efficient binding of the spike protein to its host, via the ACE-2 receptor.
The Delta variant has also acquired mutations that would allow it to evade neutralizing antibodies that serve a critical role in the body’s defense against an invading virus. This could explain why, as multiple reports have shown, the COVID-19 vaccines have been somewhat less effective against the Delta variant.
This combination of high transmissibility and immune evasion could help explain how the Delta variant became so successful.
Studies also show that people infected with the Delta variant have a higher risk of being hospitalized compared to those infected with the original SARS-CoV-2 and early variants.
One particular mutation on the spike protein of the Delta variant – the P681R mutation – is thought to be a key contributor to its improved ability to enter cells and to cause more severe disease.
Will Omicron replace Delta?
It is too early to say if the Omicron variant is fitter than Delta or if it will become dominant. Omicron shares some mutations with the Delta variant but also possesses others that are quite different.
But one of the reasons why we in the research community are particularly concerned is that the Omicron variant has 10 mutations in the receptor-binding domain – the part of the spike protein that interacts with the ACE-2 receptor and mediates entry into cells – compared with just two for the Delta variant.
Suppose the combination of all the mutations in Omicron makes it either more transmissible or better at immune evasion than Delta. In that case, we could see the spread of this variant globally. However, it is also possible that the unusually high number of mutations could be detrimental to the virus and make it unstable.
It is highly likely that the Omicron variant is not the endgame and that more SARS-CoV-2 variants will emerge. As SARS-CoV-2 continues to spread among humans, natural selection and adaptation will result in more variants that could plausibly be more transmissible than Delta.
We know from influenza viruses that the process of viral adaptation never ends.
Lower vaccination rates among many countries means that there are still a lot of susceptible hosts out there for the virus, and that it will continue to circulate and mutate as long as it can spread.
The emergence of the Omicron variant is yet another reminder of the urgency to vaccinate to stop the further spread and evolution of SARS-CoV-2.
Suresh V. Kuchipudi, Professor of Emerging Infectious Diseases, Penn State.
This article is republished from The Conversation under a Creative Commons license. Read the original article.
COVID Delta variant as transmissible as chickenpox, says CDC | Coronavirus pandemic News
Internal CDC report, quoted by NYT, says Delta variant likely to break through protections afforded by the vaccines.
The Delta variant of the coronavirus is as contagious as chickenpox and could cause severe illness, according to an internal document at the United States Centers for Disease Control and Prevention (CDC), The New York Times reported.
The variant was also more likely to break through protections afforded by the vaccines, the report said, adding that CDC’s decision to reverse course on masking guidelines for fully vaccinated citizens on Tuesday is based on the document.
The agency had previously said the vaccinated did not need to wear masks indoors.
Still, the CDC’s figures show that the vaccines are highly effective in preventing serious illness, hospitalisation and death in vaccinated people, according to experts quoted by the newspaper.
The Delta variant is more transmissible than the viruses that cause MERS, SARS, Ebola, the common cold, the seasonal flu and smallpox, the report said.
The immediate next step for the agency is to “acknowledge the war has changed”, the report cited the document as saying before adding that the CDC is expected to publish additional data on the variant on Friday.
CDC Director Rochelle Walensky told the Times that new research showed the vaccinated people infected with the Delta variant carried tremendous amounts of the virus in the nose and throat.
Officials have warned of rising COVID-19 infections in the US, particularly among about half of the population that remains unvaccinated, despite a successful rollout that has seen an excess stock of the inoculant.
The vaccine hesitancy among large swaths of the country, fuelled largely by misinformation, has scuttled the government’s hopes of controlling the virus within months of the vaccine being approved for emergency use.
Washington has resorted to increasingly blunt methods to encourage the remaining citizens to be vaccinated, including requiring federal employees to get the jab or be subject to mandatory testing and other restrictions.
On Thursday, the Biden administration called on state and local governments to offer $100 payments for newly vaccinated Americans, funded by $350bn in aid granted under the American Rescue Plan Act.