Meet the new mutant Ninja variant: Omicron. The latest in the steadily growing variants of the SARS-CoV-2 virus, Omicron shares traits with its cousins—Alpha, Beta, Gamma and Delta—but is also more evolved. Scientists have found 50 mutations in the Omicron avatar compared to 18 in Delta, of which a staggering 36 are found in the spike protein the virus uses to invade human cells. Many of these can overcome the fortifications provided by the new vaccines developed to combat Covid-19. That makes Omicron the most infectious of the coronavirus variants to have tormented the globe since December 2019. The only saving grace, if there is one, is that while it has spread more rapidly than its predecessors, it is less lethal (so far).

(Left) Crowds at Delhi’s Sarojini Nagar during Christmas; (Photo: ANI)

Consider the facts. The Omicron variant was first identified in Botswana and South Africa in November 2021. Experts now acknowledge it as the fastest-spreading variant yet, responsible for the global resurgence of Covid, adding a daily caseload of 1.7 million. In India, it has spread four times faster than Delta (which was first discovered in India in December 2020) in the second wave. India’s daily average of cases stood at 150,307 as on January 12, a number expected to quadruple in the coming weeks. According to central government sources, a genomic analysis of positive samples from across the country revealed Omicron’s presence in 85 per cent samples and the Delta strain in the remaining. “There is no doubt that the upsurge we are witnessing in India is driven and powered by Omicron,” asserts Dr V.K. Paul, member, NITI Aayog and chairman of the National Expert Group on Vaccine Administration for Covid-19 (NEGVAC). “It has dethroned Delta and is now the powerful new king of coronaviruses.”

Dr Paul’s declaration has ominous implications for the country. “The third wave is here,” says Dr Randeep Guleria, chief of AIIMS, Delhi. “This doesn’t mean we panic. We need to remedy the situation and double up on our containment efforts.” On January 11, Dr Guleria took a booster dose of the Covid vaccine in the wake of the growing number of cases in the national capital where every fourth person being tested is Covid positive. The positivity rate of 25 per cent in Delhi is the highest since May 5, 2021, when Delta was wreaking havoc. As other metros like Mumbai, Chennai and Kolkata began reporting a surge in cases, health officials in these cities reintroduced measures to slow down the spread, including weekend curfews and reimposing work-from-home norms. “There is need for zero complacency—masks, social distancing and testing are just the first line of defence,” says Dr K. Srinath Reddy, chairman of the Delhi-based PHFI (Public Health Foundation of India).

Graphics by Tanmoy Chakraborty

Is Omicron more infectious than Delta?

Omicron’s most alarming trait is its infectivity. Of the two chief parameters used to assess the speed at which an infection spreads, Omicron is ahead of Delta on both. The first is the R-value or reproductive value of the virus, which is a measure of the number of people a single infected person can spread the virus to. Currently, this stands at 2.69 in India, more than double the 1.22 maximum R-value recorded during the Delta wave in 2021. The second indicator is the positivity rate, or the number of people testing Covid positive out of 100. At 13.29 per cent on January 10 in India, the figure was more than double the WHO-recommended containment threshold of 5 per cent.

Elsewhere in the world, too, Omicron’s spread has been more rapid than Delta’s. A University of Hong Kong study suggests that Omicron is up to 70 times more transmissible than its Delta counterpart. (The study is yet to be peer-reviewed). Another study, published on the medRxiv site and also awaiting peer review, analysed 131,478 tests in France from October 25 to December 18, 2021, and found Omicron 105 per cent more contagious. In the US, analysis by experts at the Centers for Disease Control (CDC), has shown that Omicron accounted for over half of all the new cases in a little more than a month’s time since the strain was first detected. “There are specific mutations in the spike protein that make it easier for the virus to enter human cells,” explains Dr Rakesh Mishra, director of the Tata Institute of Genetics and Society in Bengaluru. Reports from the UK, the country with the greatest number of Omicron cases, show that its peak figure of new cases was four times that seen with the Delta variant.

Studies across the world also show Omicron to have a shorter incubation period—the time taken for symptoms to appear after infection—again highlighting its more infectious nature over other variants. The Alpha variant had an incubation period of six days and Delta four days. For Omicron, the average is three days. The CDC has observed that Omicron patients are the most infectious in the first two days before the symptoms manifest and continue to be so for three days after. In more than 100 studies from 17 countries, it suggested, most transmission seemed to take place early in an infection. “It is critical to get tested as soon as symptoms appear as this is the time when a person is also most likely to infect others,” says Dr Sandeep Budhiraja, the medical director of Max Super Speciality Hospitals, Saket, in Delhi.

Healthcare workers take nasal samples from passengers arrivingfrom other states at the Mumbai airport; (Photo: ANI)

Who is most vulnerable to Omicron?

Omicron seems to spare no age group, with both the young and old getting equally afflicted. Nor does it care for those who have been fully vaccinated or even infected with a different variant before. “Omicron is causing a large number of breakthrough infections,” says Budhiraja. “There is no guaranteed way to predict who will or won’t get infected.” In Maharashtra, which has reported the highest number of Omicron cases, around 81 per cent of those infected with the new strain were fully vaccinated. While there is no data in India yet about the ages of those infected, in the US, more than half the Omicron cases were among those between the ages of 18 and 39 years. “Even in the past two waves, we have seen that even if you are young and healthy, it does not mean you cannot turn Covid positive,” says Delhi-based infectious diseases specialist Dr Ankita Baidya.

In the pattern of its spread across the country, too, Omicron differs from the way Alpha (first wave) and Delta (second wave) progressed. While in the first two waves, infections spread from the south and west to the rest of the country, Omicron has had a near-simultaneous impact in cities in north and east India too. As on January 9, five states—Maharashtra, West Bengal, Delhi, Tamil Nadu and Karnataka—were reporting the maximum number of cases, with West Bengal recording the highest weekly positivity rate of 29.91 per cent and Maharashtra and Delhi averaging 17 per cent each. Cases in Bihar, Jharkhand, Chhattisgarh, Gujarat, Haryana, Punjab, Rajasthan, Uttar Pradesh and Odisha have begun to accelerate too. So rapid has been its spread that while only 78 districts reported a positivity rate above the danger mark of 5 per cent on January 4, by January 11, 300 districts across the country were reporting higher positivity rates. Among cities, Delhi and Mumbai are leading in terms of number of cases followed by Bengaluru, Pune, Chennai, and Kolkata. What’s worrying is that given its infectivity and penchant for breaching the defences of even the vaccinated, Omicron’s is, as Dr Paul puts it, “a Qutub Minar kind of rise and not a gentle rising slope. We are hoping Omicron’s fall will be as steep.”

Is Omicron milder compared to Delta?

According to a CDC study, the four most common symptoms of Omicron are a cold, fatigue, nasal congestion and a runny nose. An ongoing study by King’s College London has also recorded nausea, loss of appetite and night sweats as symptoms. Mercifully, various studies are now confirming that Omicron results in milder illness than Delta. According to a study led by researchers at South Africa’s National Institute for Communicable Diseases, individuals infected with Omicron between October and early December 2021 had 80 per cent lesser risk of hospitalisation. The study, which is yet to be peer-reviewed, also noted a 30 per cent reduction in risk of severe complications. The percentage of risk varies across countries. The UK Health Security Agency (UKHSA) says the risk of Omicron resulting in severe disease is approximately half that of Delta, and that of hospital admission approximately a third compared to Delta. CDC data shows that adults are 29 per cent less likely to be hospitalised. However, while Omicron symptoms may appear milder as compared to Delta, WHO director-general Tedros Adhanom Ghebreyesus warns, “Omicron is not the common cold.”

In India, experts attribute the public’s lack of caution towards Omicron to its relative mildness. Indeed, Omicron symptoms may not be as severe as the ones Delta triggers, but it can still cause sufficient damage on its own to keep a person bedridden for over a week. “Covid-induced fever and cold can really drain your energy,” says Dr Aditya S Chowti, senior internal medicine consultant at Fortis Hospitals, Cunningham Road, Bengaluru. “Many patients also complain of severe body and joint ache. Should you test positive, it is important to take a lot of rest and eat nutritious food to give your body the vitamins, minerals and calories it needs to cope with the illness.” Shreya Bakshi, a 34-year-old business administration student in Gurugram, learnt her lesson the hard way. “I was diagnosed with Covid recently after two days of intensely high fever and constant coughing. I had such severe body pain that I could not get out of the bed for the entire week. I have no other illnesses, although I am overweight. You hear that Covid is mild and just a fever, but the fever itself is exhausting and leaves you unable to function properly. There was also a lot of psychological trauma and stress that I might have infected others in my family.”

Is the hospitalisa­tion risk less in Omicron?

From the cases in India analysed so far, Omicron has an asymptomatic rate of 75-80 per cent, which is similar to Delta, but when it comes to serious attacks and hospitalisation, the rate is reassuringly lower. The Delta wave saw 20-25 per cent patients being admitted in hospitals, whereas only 5-10 per cent of Omicron patients have to be hospitalised, according to the Union ministry of health and family welfare (MoHFW) data. But that doesn’t mean the country should lower its guard. “With two fairly lethal waves behind us, there is some pandemic fatigue. Omicron has also brought to light new data and new misconceptions. A big part of the fight against the pandemic is information management. Less hospitalisation does not mean you take Omicron lightly,” says Dr Anupam Sibal, medical director of the Apollo Group of Hospitals.

The real risk is far higher for those with comorbid ailments such as asthma, hypertension, heart disease and cancer. Reports from Delhi’s largest Covid facility, the LNJP Hospital, reveal that most patients getting admitted have comorbidities. “It can be lethal for patients who have weak immune systems or problems in any of their organs or are recovering from surgery,” says Mumbai-based nephrologist Dr Atul Ingale. “Age, too, makes a patient more vulnerable to severe disease. All respiratory diseases, not just Covid, can cause problems in those with comorbid conditions but Covid, due to how fast it spreads, is the most concerning and the reason why we shouldn’t take it lightly.” This is why MoHFW has announced that those above 60 years and with comorbidities are eligible for a third dose of the vaccine (see accompanying report, Confidence Booster).

Patients at the Covid care facility in CWG village, Delhi; (Photo: Kamal Kishore / PTI)

Also, while the percentage of those being hospitalised may be lower, the sheer number of people getting infected and who need treatment, warn experts, may test the country’s health infrastructure. “You don’t want a tsunami of hospitalisations,” says Dr Mishra. “The chain of transmission has to be broken to keep those at high risk safe and to prevent further opportunities for the virus to mutate.” Adds Dr Paul: “The need for hospital care may increase suddenly. It is too soon to be certain about the rate of hospitalisations.” Going by the current 5-10 per cent rate of hospitalisation and an expected peak of 1 million cases a day, India would require 50,000-100,000 beds a day. and 350,000-700,000 beds at the peak, assuming that an average patient will require seven days of hospitalisation. India currently has 1.8 million isolation beds, 500,000 oxygen supported beds and 140,000 ICU beds, leaving it in a better state of preparedness than during the Delta wave. However, should infection be concentrated in a big city like Delhi, it could certainly overwhelm the capital’s health infrastructure. The good news so far is that India’s current recovery rate is 96.36 per cent and fatality rates too are much lower than those observed during the devastating Delta surge.

Why is Omicron less lethal?

To understand why Omicron has so far proved less lethal than Delta, scientists have been trying to study its progression in lab settings. Researchers at Washington University in St Louis, US, found that Omicron-infected hamsters and mice showed 10 times lower concentration of the variant in the lungs than with Delta. Researchers at the Leuven University in Belgium and the University of Liverpool, UK, made similar observations. “Studies and experiences are suggesting that Omicron infects the upper respiratory tract more and there is less chance of it triggering pneumonia,” says Dr Davindra Kundra, pulmonologist at the Manipal Hospital in Dwarka, Delhi.

Another reason for Omicron’s reduced impact relates to the memory retention of T-cells, the primary weapon of the human body’s immune system. White blood cells that can remember past diseases, they attack virus-infected cells or produce antibodies to counter them. Unlike antibodies, T-cells can target the entire spike protein, which hasn’t mutated beyond recognition in Omicron. This was confirmed in a December 10, 2021, study in BioRxiv, which showed that Omicron has not evolved enough to escape the clutches of human T-cells. These cells recognise and help clear Omicron infections before they reach the lower respiratory tract. T-cell memory in Indians could be both due to vaccination and previous Covid infection.

Yet a lot remains unknown about Omicron and its impact. “Most patients are less likely to see severe disease with Omicron,” says Dr Kundra. “But one cannot rule it out entirely yet. Moreover, some patients with mild symptoms in the previous waves had long Covid symptoms. We don’t know yet whether that will happen with Omicron.” More than 50 long-term effects of Covid-19 have been detected from around the world. The most common symptoms that can last from four to 12 weeks after acute infection are headache, fatigue, disturbed sleep, lack of concentration and body pain. Those with more severe Covid have had sudden blood clots, strokes, heart attacks and even kidney failure after recovery. “It is still too soon to ascertain how Omicron will impact human health post recovery,” says Dr V.K. Bahl, principal director of cardiac sciences at Max Healthcare in Saket, Delhi.

What is the best way to treat Omicron?

Doctors in India advise taking an RT-PCR test as soon as symptoms appear. Home kits using rapid antigen tests (RAT) should be the last resort, not the first, doctors advise. “Collecting the sample from the nasal cavity is not as simple as it looks. You need trained personnel to do it,” says Dr Arjun Dang, CEO of Dr Dang’s Lab in Delhi. India has the capacity to produce over 12 million ICMR-approved RATs per month. Available on Amazon and other e-commerce sites for as little as Rs 200, they have been flying off the shelves ever since the beginning of the third wave. But these tests have a high probability of false negatives. RT-PCR tests remain the gold standard for Covid-19 diagnosis. In an April 2021 PubMed study, researchers found that rapid tests from four of the biggest global companies accurately predicted Covid-positive results only 44.6-54.9 per cent of the time. In other words, around half the negative results could be false. Another study in Maharashtra by the ICMR (Indian Council of Medical Research) found that 34 per cent of RAT results were false negatives. “Timely diagnosis is needed,” says Dr Puneet Khanna, head of respiratory medicine at Manipal Hospitals. “Not only to ensure the correct line of treatment to follow but also to break the chain of transmission. An antigen test must be followed with RT-PCR for confirmation.”

It is also absolutely essential to consult a doctor as soon as one tests positive. “Self-medication, even for mild cases, is not recommended,” says Dr Farah Ingale, an internal medicine specialist from Mumbai. “A lot of parameters need to be considered when treating Covid. Just because a certain treatment is working for others or is in the news does not mean it will automatically work for you. Elderly patients or those with comorbidities, in particular, should take extra caution and follow up with doctors during and post Covid.” Rest, a light diet and symptom-specific medication are the best bet to fight off Covid-19.

The MoHFW has now revised its Covid management guidelines issued in September 2021. It has taken two drugs—hydroxychloroquine and ivermectin—off the list. Patients with mild symptoms are advised just paracetamol to manage fever. Inhaling Budesonide is recommended if symptoms persist beyond five days. For moderate to severe patients, the categorisation of which depends on the patient’s oxygen level and state of consciousness, the guidelines recommend the use of steroids, remdesivir and tocilizumab. And though monoclonal antibodies do not feature on the list, the demand for them is growing, as it is for other, newer forms of treatment (see New Lines of Treatment).

However, doctors warn against the indiscriminate use of newer drugs or self-medication. “With Covid, there is no one-drug-fits-all solution because the symptoms and progression of disease are different for different people, and now, also different for different variants,” says Dr Rahul Pandit, director of ICU at Fortis Hospitals, Mumbai, and a member of the state task force on Covid-19. “It is absolutely important that medicine be taken in consultation with doctors and at the right time.” The timing of the medicine, in particular, is proving to be crucial. In the last wave, for example, the indiscriminate use of steroids in the first week of symptoms (also known as the viral replication phase) actually contributed towards increasing the severity of the disease. Mucormycosis or Black Fungus was also a common side-effect of steroid use. “Our treatment for Covid-19 has advanced significantly in the past year,” says Dr Vivek Nangia, head of pulmonology at Max Saket. “But Omicron is a new variant and we are still understanding how different drugs will work. For that reason, we are being cautious in the use of medicine, including antibody cocktails.”

How long is the Omicron wave expected to last?

The government-backed Sutra, a mathematical model to track Covid spread in India, predicts that the third wave will peak at the end of the month with 400,000-800,000 new cases a day. Cities like Delhi and Mumbai will have 50,000-60,000 new cases daily. The model also predicts that the wave will decline sharply in February and end by March.

The experience in other countries is similar. It took about a month and a half for cases in the UK to start declining for three days in a row, and roughly the same span for cases in the US to come down. In South Africa, the wave ended in approximately three weeks. Experts suggest that given the fact that around 80-85 per cent of the Omicron infections are asymptomatic and with the lightning fast speed at which the virus multiplies in a given population, the wave is expected to last for a shorter duration than previous ones.

In terms of lives and livelihoods too, Omicron is expected to be less disruptive than Delta. For one, the period of mandatory quarantine is far less than that for Delta. In December, the CDC halved the isolation time in the US from 10 days to five, and the UK government from 10 days to seven. In India, a person is assumed to be negative seven days after testing positive (or if there is no fever for three straight days) as opposed to 10 days in the last wave.

The Centre has also issued guidelines specifying that while the respective state governments must ensure adequate drugs, hospital beds and oxygen supply, they should impose location-specific curfews rather than complete lockdowns across the state or country. The thumb rule is that a city or town should be locked down only if there exist signs that its hospital infra­structure is likely to collapse given the sheer volume of cases.

Will Omicron bestow natural herd immunity?

Herd immunity is the point at which a population acquires protection against a disease, either through vaccination or through naturally acquired immunity. Post the Delta wave, ICMR’s fourth sero survey noted that almost 86 per cent of Indians had antibodies against the strain. And yet it was not enough to halt the third wave. Experts believe that while Omicron infection may protect a person against the strain in the future, there is no guarantee the immunity will stand up to future variants. “Nobody should deliberately try to get infected with Covid thinking that will give them immunity,” says Dr Guleria. Experts fear that the natural vaccine theory, along with the belief that Omicron is mild, is breeding complacency among people towards Covid prevention measures. “Allowing unrestricted spread will also give the virus further chances to mutate,” warns Dr Mishra.

Interestingly, experts have noted that the virus is developing mutations that will help it infect more people but not necessarily cause more severe disease, as with Omicron. “It is in the interest of the virus to survive. As we vaccinate and gain immunity against it, it will choose mutations that help it spread. This is a common process with most RNA respiratory viruses,” says Dr Mishra. The Delta strain, for instance, had three mutations—L452R, P681R and E484Q—which, studies show, helped the virus replicate faster and evade antibodies more effectively, increasing its chances to trigger pneumonia and lung infection compared to the earlier Alpha variant. Omicron does not have these mutations. However, N501Y, a mutation that Omicron has in common with its Alpha, Beta, Gamma and Delta cousins, has been proven to increase transmissibility and facilitate immune escape. Omicron has three other mutations that are known to increase its transmissibility.

There is no guarantee, however, that Omicron’s successor will be even less lethal. “Covid remains a concerning and unpredictable disease,” warns virologist Dr Gagandeep Kang. “Even if Omicron is causing a milder disease, it does not mean Covid is over. We will see more waves and, in unvaccinated populations, we can also see the rise of new variants.” Indeed, a new Covid variant, IHU, has been spotted in France. With 46 mutations, it is yet to be dubbed a variant of interest by the WHO. But it is a sure sign that Omicron is not the last we have seen of Covid-19. Constant vigilance is key if we are to avoid going through the entire Greek alphabet.