Is Omicron more transmissible than Delta strain?

The column discusses the issues of symptoms of Omicron infections, its transmissibility, severity and the status of booster doses in India.

ByDebananda S Ningthoujam

Updated on 13 Dec 2021, 4:10 am

Representational Image (Photo: Pixabay)

Representational Image (Photo: Pixabay)

What are the major symptoms of Omicron infections? How fast does it spread? What is the severity of its infection? Early data indicate that the Omicron variant triggers the following major symptoms (TOI, Dec. 11, 2021): Fatigue, scratchy throat, mild fever, night sweats and body ache, dry cough.

The most important characteristics of a viral infection are its transmissibility (how fast does it spread), its virulence (how severe is the disease), and its vaccine resistance (what's the potential for the variant to escape immunity). As per the preliminary data, the Omicron variant is much more transmissible than the Delta strain. As the Omicron has over 30 mutations in its spike protein, it's also considered that this variant may partly escape the currently deployed vaccines, i.e. the vaccines would have lower effectiveness against the vaccines.

The good news is that Omicron seems to cause mild disease. Unlike Delta, Omicron seems not to cause high fever, persistent cough, breathlessness, chest pain, and lower blood oxygen levels. But it's too early to be definitive about these early indications, as we still don't have enough data. Therefore, we cannot afford to be complacent and must remain alert and conduct more testing, genomic surveillance, and adhere to standard SOPs to prevent transmission.

A person infected with Omicron may suffer fatigue, irritation in the throat, mild fever (that goes away on its own), night sweats (profuse sweating in the night, even if you're sleeping in a cool room), and dry cough.

Transmissibility: How fast does Omicron infections spread?

All the data generated so far indicate that Omicron is much more transmissible than the Delta variant. Even though the initial Omicron cases were detected in South Africa only on November 24, 2021, the variant has now spread to over 57 countries in such as short time. India has officially logged over 30 cases.

Even if the variant causes milder disease, unless we check its spread, there is a strong possibility that a 'wild' spread of the lineage may cause higher hospitalizations, severe strain on our healthcare systems, and even higher deaths in people with underlying conditions such as diabetes, heart or kidney diseases or immunocompromised individuals such as transplant or HIV patients.

Virulence: How severe is the Covid-19 caused by Omicron?

As explained above, the severity of COVID-19 caused by Omicron seems to be milder than that caused by Delta. However, as mentioned above, it's too early to be definitive about this. It is, therefore, necessary to follow the standard SOPs, and track the spread of this new variant by conducting more intense testing, tracing, and genomic sequencing.

Booster Shots: Will it provide significant protection?

A recent report says that the Pfizer vaccine is less effective against the Omicron variant (USA Today, Dec. 7, 2021). This study was led by Dr Alex Sigal, Africa Health Research Institute, and it showed "a very large drop in neutralization of Omicron" by the Pfizer vaccine compared to how it acted against the original coronavirus strain. The antibody response was about 41-fold lower. This means that breakthrough infections are more likely with Omicron compared to other variants of SARS-CoV-2.

It's becoming increasingly clear that only three doses of the vaccine might provide significant protection against Omicron (BBC, Dec. 10. 2021). Many countries, including US, Israel and European countries are increasing the pace of administering booster doses to their eligible populations, in preparation for tackling the new variant. Efforts are also on to develop more effective drugs and oral pills against Omicron, to help fight COVID-19, as a supplement to vaccines. Many countries have also imposed full/partial lockdowns, cancellation of international flights from certain regions, and banning entry of passengers unless they can produce negative RT-PCR reports etc.

India was going slow on boosters so far, The heartening news is that the Genome Consortium in India has now recommended booster shots for people above the age of 40 (IT, Dec. 3, 2021). However, as per latest news, India's Subject Expert Committee (SEC) has not yet approved the booster vaccine policy (TOI, Dec. 11, 2021).

Let us wait with bated breath and hope that the relevant authorities soon approve a booster dose for eligible sections of Indian population. ICMR has alo recommended a booster shot for fully vaccinated Indians, nine months after the second dose (IT, Dec. 10. 2021).

It has been shown that a booster dose of the CoviShiled vaccine provides effective protection (70-75%) against the Omicron variant (The Mint, Dec. 11, 2021).

What Does WHO Say?

The WHO has instructed countries to follow the following:

1. Increase surveillance and sequencing efforts to track circulating COVID variants.

2. Submit complete genome sequences to publicly available databases such as GISAID.

3. Report initial cases/clusters associated with VOC infections to WHO.

4. Perform field investigations and Lab assessments to improve understanding of the potential impacts of the VOC on COVID-19 epidemiology and other healthcare parameters.

Possible New Wave

It's not yet clear if a new wave of COVID-19 will emerge or not. In India, many experts opine that COVID-19 has already become an endemic and no new wave of pandemic will occur in the country. However, there is a complex interplay of new variants, vaccination rate, waning immunity and booster doses, provision of children's vaccines and easing/enforcement of restrictions and winter crowding etc. that will determine the trajectory of COVID-19 infections. We cannot afford to be complacent yet!

With COVID surging in Europe and other parts of the world, a new wave may be around the corner in India. Kerala may witness a fresh COVID wave in Jan-Feb 2022. The onset of winter, large pockets of unvaccinated people, breakthrough infections, age and other factors are some of the factors that may trigger a third wave in India (IE, Nov. 18, 2021).

New COVID Pills – possible game-changers

The new COVID drug, molnupiravir has now been approved in the UK. Thus, UK has become the first country in the world to approve this new pill. Some COVID treatments including some manufactured antibody drugs could become ineffective due to the new mutations present in Omicron, according to Dr David Ho of Columbia University.

However, experimental antiviral pills such as Paxlovid (Pfizer Inc.) and molnupiravir (Merck & Co) target parts of the coronavirus that are not changed in Omicron. These new drugs could become game-changers in the new scenario.

We can only hope that molnupiravir and paxlovid will soon arrive in India and these anti-COVID oral pills arrive in Manipur and help prevent a third wave, or blunt the impacts, in case a third wave emerges!

14 preventive steps for Manipur

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

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

3. 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.

4. Regular & repeated COVID testing in hotspots.

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

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

7. 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.

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

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

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

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

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

14. 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.

As an editorial in the prestigious medical journal, The Lancet Microbe (Jan. 1, 2021) says, "Vaccines will be instrumental in the control of COVID-19, but their global distribution will be challenging and their effect won't be immediate." So, in the meantime, we must not let our guards down and we must still strictly observe the non-pharmaceutical interventions such as the major SOPs of the use of face masks, physical distancing, and hand hygiene and avoidance of 3 Cs: crowded places, close contact settings, and closed spaces (with poor ventilation). We must religiously follow the protocol of 'test, track, and treat' for months to come. If possible, the public health authorities must take steps to prevent large gatherings such as weddings and death ceremonies, music concerts, and large meetings. The 'hoi polloi' must voluntarily practice the 3 Ws (watch your distance, wear your masks, wash your hands frequently) and avoid the 3 Cs: crowded places, closed contact settings, and closed spaces.

Meanwhile, we must enhance the pace of vaccinations across India, including Manipur, in a big way.

(The views expressed is personal)


First published:11 Dec 2021, 3:18 pm


Debananda S Ningthoujam

Debananda S Ningthoujam

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

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