Omicron Variant: Its symptoms, infectivity and vaccine resistance

Even if Omicron is milder than Delta, we cannot take things lying done; complacency on the part of health authorities, the common people, and the political leaders could lead to catastrophic consequences.

ByDebananda S Ningthoujam

Updated 2 Jan 2022, 6:19 am

Representational Image (Photo: Pixabay)
Representational Image (Photo: Pixabay)

Omicron Symptoms

The Omicron variant is spreading like wildfire across the world. It has so far reached more than 100 countries and over 22 states in India. In some places, Omicron has superseded Delta as the dominant strain.

One more worry is that this variant manifests symptoms which are quite different from that of Delta. Majority of cases may be asymptomatic or mild, similar to that of flu or common cold; making it rather difficult to ascertain if you're suffering from common cold/flu or Omicron infection. What are its typical symptoms?

According to the UK Zoe COVID study, the common symptoms of Omicron are:

Mild fever

Scratchy throat

Runny nose


Intense body pain


Night sweats.

Apart from the aforementioned symptoms, recently reported symptoms include nausea, vomiting, and loss of appetite. Another unusual symptom observed by the Zoe COVID study is skin rash (TOI, Dec. 30, 2021). This could be a manifestation of the inflammation triggered by the SARS-CoV-2 coronavirus. Skin rash could include COVID fingers and toes (also called chilblain), that could lead to red and purple bumps on fingers and toes, which could induce pain and itchiness. Two more types of rash may also emerge: hive-type and prickly heat type rash.

If you see any of these symptoms, the most prudent response must be to get yourself tested and stay isolated, till you get a negative test report.

Transmissibility of Omicron

In just over two months, Omicron has spread to more than 100 countries. What's concerning is that the variant can also infect vaccinated people and those with prior COVID infections. This highly contagious strain has now spread to more than 22 states in India. The country has now logged 1,431 Omicron infections; with a total of 22,775 COVID cases and 406 deaths in the last 24 hours (IE, Jan. 1, 2022). Omicron is considered to be 3-6 times more transmissible than Delta.

This variant has a superior capacity to cause breakthrough infections in fully vaccinated people and reinfections in people who had been previously infected. Why is Omicron spreading at lightning speed? We have no clear-cut answers. However, we have some initial clues as to why this variant is so infective (infectious).

First, Omicron has the ability to evade our immunity after vaccination and/or prior infection. Second, the variant's many (more than 30) mutations on the spike protein allows it to infect human cells more efficiently compared to previous variants. A new study from Denmark indicates that the variant's dominance largely boils down to its ability to escape the body's immune defenses (NPR, Dec. 31, 2021).

It seems to be the case that, in unvaccinated people, both Delta and Omicron have almost the same rates of infection. In other words, Omicron's increased infectivity could be mainly ascribed to its "immune evasiveness." More of the vaccinated people are now contagious and shedding the virus, according to a study led by Dr Don Milton, University of Maryland, USA. However, it must be pointed out that these findings are yet to be peer-reviwed. If you're vaccinated, it doesn't mean that you're not going to transmit it to somebody else.

Omicron may also have additional advantages, besides its capacity to evade the immune response. Maybe the variant can produce more copies of itself in a cell it infects, maybe it binds to cells more effectively, or maybe it's better at thriving in the air longer and staying infectious, says Dr Joshua Schiffer, Fred Hutchinson Cancer Research Center, USA. All of these things make Omicron highly contagious. We need not panic, but we must remain extremely cautious. The reports that Omicron causes milder disease mustn't make us complacent. The best approach should be, prepare for the worst, and hope for the best!

According to a Hong Kong study done in mid-December, Omicron multiplied about 70 times faster than delta in bronchial tissue samples. It had more trouble infecting cells in lung tissue compared to the original Wuhan strain. Respiratory secretions from your upper respiratory tracts ejected as mucus (if you got a runny nose) or exhaled as aerosols and droplets can stay suspended in the air, especially in places with poor ventilation. With Omicron, you could be shedding more infectious viral particles in your upper respiratory tract than you would be if most of the viral replication was taking place deep in the lungs, according to Angie Rasmussen, University of Saskatchewan, Canada.

Omicron probably requires a smaller dose than previous variants to infect people, although this isn't substantiated by published data as yet, according to Dr Michael Klompas, Brigham and Women's Hospital, USA (IE, Jan. 1, 2022).

Vaccine Resistance


Scientists have tried to explain how Omicron can infect vaccinated people. It seems the spreads directly from one cell to another, as there is no immunity to prevent them there. A new study suggests that the virus could be using an underground form of transmission, hiding from the immune system and spreading from cell to cell. The viral particles remain hidden within cell membranes; the target cell thus becomes a donor cell, evading the "watchful eyes" of the immune system. These findings led by Shan-Lu Liu, Ohio State University, has been published in PNAS, USA (HT, Dec. 25, 2021).

Thus, vaccines and booster doses may not be the only answer to Omicron and other future variants. There is critical need to develop effective antiviral drugs targeting other steps of viral infection. The most important SOP in our disposal is adherence of COVID-appropriate behaviour (CAB).

The highly transmissible nature of Omicron and its capacity to cause breakthrough infections and reinfections, and the fact that several people with no travel history have now tested positive in India must awaken our policymakers, common people, and political leaders to take the Omicron threat very seriously and take concerted action to prevent a third wave in India (and Manipur).

The first step could be tremendously increasing the daily testing numbers. Second, conducting routine RT-PCR tests for suspected samples. Third, performing special RT-PCR testing fro all positive samples, with a kit targeting the S-gene target. Lastly, genome sequencing of samples found positive in RT-PCR (The Hindu, Jan. 1, 2022).

It would rather be tragic for millions of 'common Indians' if we repeat the same mistakes we all committed during the onset of second COVID wave in India.

Disease Severity

Although it's widely reported that Omicron causes milder disease, how mild or severe the disease resulting from Omicron infection is yet to be fully ascertained. There are some early indications about why this variant is likely to elicit milder disease. The likely reason is that Omicron attacks mostly the upper respiratory tract and avoids infecting the lungs. Studies on mice and hamsters indicated that Omicron produced less damaging infections in the lungs; it was largely confined to the nose, throat, and windpipe.

"The idea of a disease that manifests itself primarily in the upper respiratory tract is emerging", according to Roland Ellis, Berlin Institute of Health (Times of Israel, Dec. 31, 2021). Ravindra Gupta, Cambridge University, says "The biology of the virus is not the same as it was before. It's almost a new thing."

However, the UN Health Agency cautions that "The overall risk related to the new variant of concern Omicron remains very high." According to the WHO Chief, Omicron acting in concert with Delta, could trigger not a wave but a 'Tsunami of Infections."

Even if Omicron is milder than Delta, we cannot take things lying done; complacency on the part of health authorities, the common people, and the political leaders could lead to catastrophic consequences. Let's remember that a small percentage of a huge number is still a big number. The unusually high contagiousness of Omicron could still lead to more hospitalizations and deaths. In addition, it could seriously strain our healthcare systems which are already functioning in sub-optimal conditions. Moreover, if large numbers of healthcare workers become infected, it could lead to acute shortage of doctors and nurses: manpower critical to tracing, testing, monitoring, vaccinating, and treating positive individuals.

There are, of course, contradictory reports in the media and scientific publications. An Imperial College of London (ICL) study reported that the chances of hospitalization from Omicron infection is much less than from Delta. It also showed that 2 vaccine doses were not enough to provide significant protection and that boosters are the safest way to protect against serious illness from Omicron and Delta.

Neil Ferguson, who led this study, while breaking the good news still warned that the sheer number of infections from Omicron would lead to more hospital admissions eventually. Omicron cases are currently spiraling across the world. The US and the UK are reporting record daily cases of 5-6 lakhs and 1-2 lakhs respectively. Even assuming 40-50% less severity, if there are 3-6 times more cases, that will result still in more hospitalizations and deaths than what we saw with Delta.

Another aspect which we mostly ignore is this: if positive cases rise steeply, it could have adverse pervasive impacts. More and more people would need to be isolated and go off work. This would seriously affect transport, police, fire, and healthcare services. In addition, we're not sure if Omicron would cause mild diseases in the elderly, co-morbid patients, and the unvaccinated. Also, what about LONG COVID after Omicron infections?

We need to be very careful about the messaging. If we frequently harp upon the milder nature of Omicron, this will cause general complacency. This would lead to fewer testing, tracking, vaccinations; and less adherence to standard SOPs: masking, sanitizing, and distancing as well as ventilating indoor spaces. Another compounding factor would be crowding outdoors due to political, cultural, and religious events. We must remember that the Virus's dharma and karma is finding a suitable host, replicating as fast as it could, and infecting more and more hosts. The virus doesn't bother if the crowd is of religious, cultural, or political nature!

Overstressing on the "milder" narrative may well come back to haunt some of our world leaders who are keeping their eyes closed, and their fingers crossed (Aljazeera, Dec. 28, 2021).

A Possible Third Wave

In just about a month, Omicron has surged from zero to 22 states in India. The latest Omicron tally is now 1,431. Daily COVID cases are also rising from less than 10,000  a few weeks earlier, to more than 22,000 now. Further, we've doubly vaccinated just about 60% of the eligible population in India, and boosters are yet to be administered.

In addition, night curfews combined with huge daytime gatherings for political rallies and meetings in poll-bound states do not bode well for the COVID trajectory in India.

A multi-pronged approach can only prevent or mitigate the third COVID wave in India triggered by Omicron, and compounded by Delta:

Enhanced tracking, testing, and isolation measures,

Strict surveillance of positive cases, including genomic surveillance,

Completing the single dose vaccination of the entire eligible population,

Enhancing double vaccination rate from 60 to 70% in next few weeks,


Strengthening healthcare infrastructure especially in rural, remote, and peripheral areas e.g. the North East,

Limiting crowding in public spaces such as markets, malls, and halls,

Conducting election campaigns, at least, partly in the virtual mode; as lections are unlikely to be postponed; and limiting the crowds in meetings, rallies, and campaigns to the minimum possible.

We also need to remember that vaccines and boosters may not protect us against Omicron infections but they will go a long way in protecting us from serious hospitals and possible deaths.

In addition, hospitals including those in Manipur need to stockpile the new anti-COVID drugs such as molnupiravir, paxlovid, and PBI-0451 (experimental drug, a protease inhibitor, made by the firm, Pardes Biosciences), as and when they become available (Al Jazeera, Dec. 28, 2021).

Possible Measures for Manipur

We need to assume that there may be a third wave in Manipur too. Even if that may turn out to be a wrong anticipation, it's better to err on the side of caution. Accordingly, we must initiate measures to squarely face a possible third wave in our state. These may include:

Preparations for administering vaccines to kids in Manipur & booster shots to high-risk people (elderly, healthcare workers and people with weak immune systems).

Conducting immediate seroprevalence studies to understand what percent of population in Manipur and in its different districts are still susceptible to the coronavirus.

Speeding up vaccinations in a big way; aggressive vaccinations with monthly targets to cover all eligible population with first doses in the next few weeks (4-6 weeks); and targeted vaccinations of all adult population with second doses in the next 2-3 months.

Regular & repeated COVID testing in hotspots.

Enhancing the ratio of RT-PCT to Rapid Antigen Testing (RAT).

Weekly "awareness messaging" about the pandemic to the public by a designated healthcare official.

Genomic sequencing of a subset of positive cases and surveillance of the variants including the delta variant: which COVID strains are there in Manipur, where are they, and where are they moving towards; and whether any new variants are emerging.

Contact tracing and government-monitored isolation of positive cases, wherever feasible.

Boosting up healthcare provisions such as medical oxygen plants, tankers and cylinders; steroids, antifungal drugs, oxygen concentrators, ventilators, oximeters, masks, PPEs, sanitizers etc.

Strengthening of healthcare infrastructure such as construction of new COVID hospitals.

Provision of more COVID care centres (CCCs), more Covid beds and ICUs in existing hospitals

Constitution of a special taskforce for the third wave; a separate taskforce for pediatric COVID is also highly recommended.

Special provisions for kids such as pediatric hospitals, wards, and ICUs, pediatric oximeters, concentrators, and ventilators and strengthening of staff such as pediatricians and pediatric nurses and paramedical workers etc.

Conducting, at least, part of the election campaign in the online mode, limiting crowds in public spaces, and minimizing crowds in offline cultural, political, and political events; as far as feasible.

We all owe it to the common people of Manipur to religiously adhere to the standard SOPS to help prevent/mitigate a possible third wave in Manipur; and, help save our people from possible hospitalizations and deaths.


First published:


vaccinevariant of concernomicron variantomicron symptomsomicron transmissibility

Debananda S Ningthoujam

Debananda S Ningthoujam

The author teaches and studies microbial biochemistry and biotechnology at Manipur University


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