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How bad is Omicron? What scientists know so far / Omicron किती वाईट आहे? शास्त्रज्ञांना आतापर्यंत काय माहित आहे

 How bad is Omicron? What scientists know so far 

Omicron किती वाईट आहे? शास्त्रज्ञांना आतापर्यंत काय माहित आहे 

COVID researchers are working at breakneck speed to learn about the variant’s transmissibility, severity and ability to evade vaccines.

कोविड संशोधक या प्रकाराची संक्रमणक्षमता, तीव्रता आणि लस टाळण्याची क्षमता जाणून घेण्यासाठी अत्यंत वेगाने काम करत आहेत.


A nurse puts on her personal protective equipment

South Africa is dealing with a large uptick in COVID cases, driven by a new, heavily mutated variant called Omicron.Credit: Guillem Sartorio/AFP/Getty

दक्षिण आफ्रिका ओमिक्रोन नावाच्या नवीन, जोरदारपणे उत्परिवर्तित व्हेरिएंटद्वारे चालवलेल्या कोविड प्रकरणांमध्ये मोठ्या प्रमाणात वाढ करत आहे. क्रेडिट: गुइलम सारटोरियो/एएफपी/गेट्टी

Barely a week has elapsed since scientists in Botswana and South Africa alerted the world to a fast-spreading new SARS-CoV-2 variant now known as Omicron. Researchers worldwide are racing to understand the threat that the variant — now confirmed in more than 20 countries — poses to the world. Yet it might take scientists weeks to paint a more complete picture of Omicron, and to gain an understanding of its transmissibility and severity, as well as its potential to evade vaccines and cause reinfections.

बोट्सवाना आणि दक्षिण आफ्रिकेतील शास्त्रज्ञांनी जगाला झपाट्याने पसरणाऱ्या नवीन SARS-CoV-2 प्रकाराबाबत सतर्क केल्यापासून जेमतेम एक आठवडा उलटून गेला आहे, ज्याला आता Omicron म्हणून ओळखले जाते. जगभरातील संशोधक या प्रकाराचा – आता 20 पेक्षा जास्त देशांमध्ये पुष्टी झालेला – जगासमोर असलेला धोका समजून घेण्यासाठी धडपडत आहेत. तरीही शास्त्रज्ञांना ओमिक्रॉनचे अधिक संपूर्ण चित्र रंगविण्यासाठी आणि त्याची संक्रमणक्षमता आणि तीव्रता तसेच लस टाळण्याची आणि पुनर्संक्रमणास कारणीभूत होण्याची क्षमता समजून घेण्यासाठी काही आठवडे लागू शकतात.


“Wherever I go, everyone says: tell us more about Omicron,” says Senjuti Saha, molecular microbiologist and director of the Child Health Research Foundation in Dacca, Bangladesh. “There is so little understanding of what’s going on, and that’s true, even for scientists.”

Nature rounds up what scientists know so far about the Omicron variant.

बांग्लादेशातील डक्का येथील चाइल्ड हेल्थ रिसर्च फाउंडेशनच्या आण्विक सूक्ष्मजीवशास्त्रज्ञ आणि संचालिका सेंजुती साहा म्हणतात, “मी जिथे जातो तिथे प्रत्येकजण म्हणतो: आम्हाला ओमिक्रॉनबद्दल अधिक सांगा. “काय चालले आहे याबद्दल खूप कमी समज आहे आणि ते अगदी शास्त्रज्ञांसाठीही खरे आहे.”

Omicron प्रकाराबद्दल शास्त्रज्ञांना आतापर्यंत जे माहीत आहे ते निसर्गाने मांडले आहे.


How fast is Omicron spreading?

Omicron’s rapid rise in South Africa is what worries researchers most, because it suggests the variant could spark explosive increases in COVID-19 cases elsewhere. On 1 December, South Africa recorded 8,561 cases, up from the 3,402 reported on 26 November and several hundred per day in mid-November, with much of the growth occurring in Gauteng Province, home to Johannesburg.

Omicron किती वेगाने पसरत आहे?

दक्षिण आफ्रिकेत ओमिक्रॉनची झपाट्याने होणारी वाढ ही संशोधकांना सर्वात जास्त चिंतित करते, कारण ते सूचित करते की या प्रकारामुळे इतरत्र कोविड-19 प्रकरणांमध्ये स्फोटक वाढ होऊ शकते. 1 डिसेंबर रोजी, दक्षिण आफ्रिकेत 8,561 प्रकरणे नोंदवली गेली, जी 26 नोव्हेंबर रोजी नोंदवण्यात आलेल्या 3,402 पेक्षा जास्त आणि नोव्हेंबरच्या मध्यात दररोज अनेक शंभर प्रकरणे नोंदवली गेली, ज्यात बरीच वाढ जोहान्सबर्गचे घर असलेल्या गौतेंग प्रांतात झाली.


एपिडेमियोलॉजिस्ट R वापरून महामारीच्या वाढीचे मोजमाप करतात, प्रत्येक संसर्गामुळे पसरलेल्या नवीन प्रकरणांची सरासरी संख्या. नोव्हेंबरच्या अखेरीस, जोहान्सबर्गमधील दक्षिण आफ्रिकेच्या नॅशनल इन्स्टिट्यूट फॉर कम्युनिकेबल डिसीज (NICD) ने निर्धारित केले की गौतेंगमध्ये R 2 च्या वर आहे. दक्षिण आफ्रिकेतील डर्बन येथील क्वाझुलु-नॅटल युनिव्हर्सिटीमधील संसर्गजन्य-रोग चिकित्सक रिचर्ड लेसेल्स यांनी गेल्या आठवड्यात एका पत्रकार परिषदेत सांगितले की, साथीच्या रोगाच्या सुरुवातीच्या दिवसांमध्ये वाढीचा हा स्तर शेवटचा दिसून आला.

Gauteng’s R value was well below 1 in September — when Delta was the predominant variant and cases were falling — suggesting that Omicron has the potential to spread much faster and infect vastly more people than Delta, says Tom Wenseleers, an evolutionary biologist at KU-Leuven in Belgium. Based on the rise in COVID-19 cases and sequencing data, Wenseleers estimates that Omicron can infect 3 to 6 times as many people as Delta, over the same time period. “That’s a huge advantage for the virus — but not for us,” he adds.

सप्टेंबरमध्ये गौतेंगचे आर मूल्य 1 च्या खाली होते — जेव्हा डेल्टा हा मुख्य प्रकार होता आणि केसेस कमी होत होत्या — असे सुचविते की ओमिक्रॉनमध्ये डेल्टा पेक्षा खूप वेगाने पसरण्याची आणि मोठ्या प्रमाणावर लोकांना संक्रमित करण्याची क्षमता आहे, टॉम वेन्सेलर्स, KU-Leuven येथील उत्क्रांतीवादी जीवशास्त्रज्ञ म्हणतात. बेल्जियम मध्ये. कोविड-19 प्रकरणांमध्ये झालेली वाढ आणि अनुक्रमांक डेटाच्या आधारे, वेन्सेलर्सचा अंदाज आहे की ओमिक्रॉन त्याच कालावधीत डेल्टाच्या 3 ते 6 पट जास्त लोकांना संक्रमित करू शकते. “व्हायरससाठी हा एक मोठा फायदा आहे – परंतु आमच्यासाठी नाही,” तो पुढे म्हणाला.

Researchers will be watching how Omicron spreads in other parts of South Africa and globally to get a better read on its transmissibility, says Christian Althaus, a computational epidemiologist at the University of Bern, Switzerland. Heightened surveillance in South Africa could cause researchers to overestimate Omicron’s fast growth. But if this pattern is repeated in other countries, it’s very strong evidence that Omicron has a transmission advantage, adds Althaus. “If it doesn’t happen, for example, in European countries, it means things are a bit more complex and strongly depend on the immunological landscape. So we have to wait.”

स्वित्झर्लंडच्या बर्न विद्यापीठातील संगणकीय महामारीशास्त्रज्ञ ख्रिश्चन अल्थॉस म्हणतात की, दक्षिण आफ्रिकेच्या इतर भागांमध्ये आणि जागतिक स्तरावर ओमिक्रॉनचा प्रसार कसा होतो यावर संशोधक लक्ष ठेवतील. दक्षिण आफ्रिकेतील वाढीव निगराणीमुळे संशोधकांना ओमिक्रॉनच्या वेगवान वाढीचा अंदाज येऊ शकतो. परंतु हा पॅटर्न इतर देशांमध्ये पुनरावृत्ती झाल्यास, ओमिक्रॉनला ट्रान्समिशनचा फायदा असल्याचा हा खूप मजबूत पुरावा आहे, अल्थॉस जोडते. “जर असे झाले नाही, उदाहरणार्थ, युरोपियन देशांमध्ये, याचा अर्थ गोष्टी थोड्या अधिक क्लिष्ट आहेत आणि इम्यूनोलॉजिकल लँडस्केपवर जोरदार अवलंबून आहेत. त्यामुळे आम्हाला वाट पहावी लागेल.”

Although genome sequencing is needed to confirm Omicron cases, some PCR tests can pick up a hallmark of the variant that distinguishes it from Delta. On the basis of this signal, there are preliminary signs that cases, although extremely low in number, are rising in the United Kingdom. “That’s certainly not what we want to see right now and suggests that Omicron could indeed also have a transmission advantage in the UK,” Althaus adds.

जरी ओमिक्रॉन प्रकरणांची पुष्टी करण्यासाठी जीनोम अनुक्रमणाची आवश्यकता असली तरी, काही पीसीआर चाचण्या डेल्टा पेक्षा वेगळे असलेल्या प्रकाराचे वैशिष्ट्य दर्शवू शकतात. या संकेताच्या आधारे, युनायटेड किंगडममध्ये प्रकरणे अत्यंत कमी असली तरी, वाढत असल्याची प्राथमिक चिन्हे आहेत. अल्थॉस जोडते, “आम्हाला आत्ता ते नक्कीच पहायचे नाही आणि असे सुचविते की ओमिक्रॉनला खरोखरच यूकेमध्ये ट्रान्समिशनचा फायदा होऊ शकतो.”

Can Omicron overcome immunity from vaccines or infection?

The variant’s swift rise in South Africa hints that it has some capacity to overcome immunity. Around one-quarter of South Africans are fully vaccinated, and it’s likely that a large fraction of the population was infected with SARS-CoV-2 in earlier waves, says Wenseleers, based on heightened death rates since the start of the pandemic.

ओमिक्रॉन लस किंवा संसर्गापासून प्रतिकारशक्तीवर मात करू शकते?
दक्षिण आफ्रिकेमध्ये या प्रकाराचा झपाट्याने वाढ होणे हे सूचित करते की त्यात प्रतिकारशक्तीवर मात करण्याची काही क्षमता आहे. सुमारे एक चतुर्थांश दक्षिण आफ्रिकेचे पूर्णपणे लसीकरण झाले आहे, आणि बहुधा लोकसंख्येचा मोठा भाग SARS-CoV-2 ने पूर्वीच्या लहरींमध्ये संक्रमित झाला होता, असे Wenseleers म्हणतात, साथीच्या रोगाच्या सुरुवातीपासून वाढलेल्या मृत्यूच्या दरावर आधारित.
In this context, Omicron’s success in southern Africa might be due largely to its capacity to infect people who recovered from cases of COVID-19 caused by Delta and other variants, as well as those who’ve been vaccinated. A 2 December preprint1 from researchers at the NICD found that reinfections in South Africa have increased, as Omicron has spread. “Unfortunately, this is the perfect environment for immune escape variants to develop,” says Althaus.
या संदर्भात, दक्षिण आफ्रिकेतील ओमिक्रॉनचे यश हे डेल्टा आणि इतर प्रकारांमुळे झालेल्या COVID-19 च्या प्रकरणांमधून बरे झालेल्या तसेच लसीकरण झालेल्या लोकांना संक्रमित करण्याच्या क्षमतेमुळे असू शकते. NICD मधील संशोधकांच्या 2 डिसेंबरच्या प्रीप्रिंट 1 मध्ये असे आढळून आले की दक्षिण आफ्रिकेमध्ये ओमिक्रॉन पसरल्यामुळे पुन्हा संसर्ग वाढला आहे. “दुर्दैवाने, रोगप्रतिकारक शक्तीच्या सुटकेसाठी हे योग्य वातावरण आहे,” अल्थॉस म्हणतात.
How well the variant spreads elsewhere might depend on factors such as vaccination and prior infection rates, says Aris Katzourakis, an expert in viral evolution at the University of Oxford, UK. “If you throw it into the mix in a highly vaccinated population that has given up on other control measures, it might have the edge there.”
युनिव्हर्सिटी ऑफ ऑक्सफर्ड, यूके मधील व्हायरल उत्क्रांती तज्ञ अॅरिस कॅटझोराकिस म्हणतात, हा प्रकार इतरत्र किती चांगल्या प्रकारे पसरतो हे लसीकरण आणि अगोदर संक्रमण दर यासारख्या घटकांवर अवलंबून असू शकते. “तुम्ही इतर नियंत्रण उपायांचा त्याग केलेल्या उच्च लसीकरण झालेल्या लोकसंख्येमध्ये मिश्रणात टाकल्यास, त्यास कदाचित तेथे धार मिळेल.”
Researchers want to measure Omicron’s ability to evade immune responses and the protection they offer. For instance, a team led by Penny Moore, a virologist at the NICD and the University of Witwatersrand in Johannesburg, is measuring the ability of neutralizing, or virus-blocking, antibodies triggered by previous infection and vaccination to stop Omicron from infecting cells, in a laboratory test. Her team is making ‘pseudovirus’ particles — an engineered version of HIV that uses SARS-CoV-2’s spike protein to infect cells — to match Omicron, which harbours as many as 32 changes to spike.
Another South Africa-based team, led by virologist Alex Sigal at the African Health Research Institute in Durban, is conducting similar tests on virus-neutralizing antibodies using infectious SARS-CoV-2 particles. So is a team led by Pei-Yong Shi, a virologist at the University of Texas Medical Branch in Galveston, who is collaborating with Pfizer–BioNtech to determine how its vaccine holds up against Omicron. “I was really very concerned when I saw the constellation of mutations in the spike,” he says. “We just have to wait for the results.”
Previous studies of Omicron’s spike mutations — particularly in the region that recognizes receptors on human cells — suggest that the variant will blunt the potency of neutralizing antibodies. For instance, in a September 2021 Nature paper2, a team co-led by Paul Bieniasz, a virologist at Rockefeller University in New York City, engineered a highly mutated version of spike — in a virus incapable of causing COVID-19 — that shares numerous mutations with Omicron. The ‘polymutant spike’ proved fully resistant to neutralizing antibodies from most of the people they tested who had either received two doses of an RNA vaccine or recovered from COVID-19. With Omicron, “we expect there to be a significant hit,” says Bieniasz..

How will vaccines fare against Omicron?

If Omicron can dodge neutralizing antibodies, it does not mean that immune responses triggered by vaccination and prior infection will offer no protection against the variant. Immunity studies suggest that relatively low levels of neutralizing antibodies may protect people from severe forms of COVID-19, says Miles Davenport, an immunologist at the University of New South Wales in Sydney, Australia.

Other parts of the immune system, particularly T cells, may be less affected by Omicron’s mutations than are antibody responses. Researchers in South Africa plan to measure the activity of T cells and another immune player called natural killer cells, which may be especially important for protection against severe COVID-19, says Shabir Madhi, a vaccinologist at the University of Witwatersrand.

Madhi, who has led COVID-19 vaccine trials in South Africa, is also part of efforts to conduct epidemiological studies of vaccines’ effectiveness against Omicron. There are anecdotal reports of breakthrough infections in all three vaccines that have been administered in South Africa – Johnson & Johnson, Pfizer–BioNtech and Oxford–AstraZeneca. But Madhi says researchers will want to quantify the level of protection provided by vaccines, as well as prior infection against Omicron.

He suspects that the results will be reminiscent of how the AstraZeneca–Oxford vaccine performed against the Beta variant, an immune-evading variant that was identified in South Africa in late 2020. A study led by Madhi found that the vaccine offered little protection against mild and moderate cases in relatively young people, while a real-world analysis in Canada showed greater than 80% protection against hospitalization.

If Omicron behaves similarly, Madhi says, “we’re going to see a surge of cases. We’re going to see lots of breakthrough infections, lots of reinfections. But there’s going to be this unhinging of the case rate in the community compared to the hospitalization rate”. Early reports suggest that most breakthrough infections with Omicron have been mild, says Madhi. “For me, that is a positive signal.”

Will current boosters improve protection against Omicron?

The threat of Omicron has prompted some rich countries, such as the United Kingdom, to accelerate and broaden the roll-out of COVID vaccine booster doses. But it’s not yet clear how effective these additional doses will be.

Third doses supercharge neutralizing-antibody levels, and it’s likely that this will provide a bulwark against Omicron’s ability to evade these antibodies, says Bieniasz. His team’s work on the polymutant spike found that people who had recovered from COVID-19 months before receiving their jabs had antibodies still capable of blocking the mutant spike. To Bieniasz, those results suggest that people with repeated exposure to SARS-CoV-2’s spike protein, be it through infection or a booster dose, are “quite likely to have neutralizing activity against Omicron.”

Does Omicron cause milder or more severe disease than previous variants?

Early reports linked Omicron with mild disease, raising hopes that the variant might be less severe than some of its predecessors. But these reports — which are often based on anecdotes or scant scraps of data — can be misleading, cautions Müge Çevik, an infectious disease specialist at the University of St Andrews, UK. “Everyone is trying to find some data that could guide us,” she says. “But it’s very difficult at the moment.”

A major challenge when assessing whether a variant’s severity is controlling for the many confounding variables that can influence the course of disease, particularly when outbreaks are geographically localized. For example, reports of mild disease from Omicron infection in South Africa could reflect the fact that the country has a relatively young population, many of whom have already been exposed to SARS-CoV-2.

During the early days of the Delta outbreak, there were reports that the variant was causing more serious illness in children than other variants — an association that dissolved once more data were collected, Çevik says.

Researchers will be looking for data on Omicron infections in other countries. This geographical spread, and a larger sample size as cases accrue, will give researchers a better idea of how generalizable the early anecdotes might be.Ultimately, researchers will want to conduct case-controlled studies in which the demographics of people infected with Omicron are carefully matched to the demographics of a comparison group. This will allow scientists to better control for important factors, such as age, vaccination status and health conditions. Data from both groups will need to be collected contemporaneously, because the number of hospitalizations can be influenced by overall hospital capacity in a region.

And, crucially, researchers will need to control for the level of economic deprivation. A rapidly spreading new variant may reach vulnerable groups more rapidly, Çevik says, by nature of their work or living conditions. And such groups often experience more severe disease.

All of this will take time. “I think the severity question will be one of the last bits that we’ll be able to untangle,” she says. “That’s how it happened with Delta.”

Where has Omicron spread and how are scientists tracking it?

So far, Omicron has been detected in more than 20 countries, a number that has been steadily ticking up as efforts to track the variant increase around the world.

But the capacity to rapidly sequence viruses from positive COVID tests is concentrated in wealthy countries, meaning that early data on Omicron’s spread will be skewed.

Surveillance efforts in Brazil and some other countries are taking advantage of a distinctive result on particular PCR tests for COVID that could allow them to pinpoint potential Omicron cases for sequencing, says virologist Renato Santana at the Federal University of Minas Gerais in Brazil. The test looks for segments of three viral genes, one of which is the gene that encodes for the spike protein. Mutations in Omicron’s spike gene prevent its detection in the test, meaning that samples containing the variant will only test positive for two of the genes.

Even so, not everyone uses that kit and it could take some time before Omicron’s spread is fully mapped. Despite some guidelines urging countries to sequence 5% of their samples that test positive for SARS-CoV-2, few countries can afford to do so, says computational virologist Anderson Brito at the All for Health Institute in São Paulo, Brazil.And Brito worries that the travel bans some countries enacted against South Africa and other southern African nations in the wake of its Omicron discovery could discourage governments from sharing their surveillance data. “We are punishing those who did a good job,” he says.

In Bangladesh, which sequences about 0.2% of positive coronavirus samples, researchers would be eager to ramp up genomic surveillance to monitor for Omicron and other emerging variants, says molecular microbiologist Senjuti Saha, a molecular microbiologist and director of the Child Health Research Foundation in Dhaka. But resources are limited. Bangladesh is recovering from a large dengue outbreak, she adds. “In the Global South, we are all worried about COVID, but let’s not forget our endemic diseases,” Saha says. “We can only do so many.”

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