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Omicron Threat: Its transmissibility, vaccine escape potential

Vaccine effectiveness against symptomatic Omicron infection is 0-20 per cent after two vaccine doses, and between 55 per cent and 80 per cent after booster shots.

ByDebananda S Ningthoujam

Updated on 19 Dec 2021, 9:31 am

Representational Image (Photo: Pixabay)

Representational Image (Photo: Pixabay)

A Possible Third Wave

If a surge happens in India, like the one taking place in the UK, triggered by the latest variant called Omicron, there may be a third coronavirus wave in India. Experts have predicted that there could be 14-15 lakh daily cases in our country, if the present level of complacency, vaccinations, and booster shots continue (TOI, Dec. 18, 2021).

The UK reported 80,000 cases on Dec. 16 and France 65,000. But these are tiny nations. If that trend is extrapolated to the huge population of India, you may well imagine the situation that may arise; god forbid the situation from arising in the first place.

However, a few things are concerning, the rate of full vaccinations in India is still low, there is no policy yet for administering booster doses, compounded by the onset of winter, people traveling and congregating for Xmas, and New Year celebrations. Add to this the crowding for upcoming elections in 5 states. All these factors plus Omicron: you indeed get a heady cocktail!

Omicron: Major Symptoms

Early data indicate that the Omicron variant triggers the following major symptoms (TOI, Dec. 11, 2021):

- Fatigue

- Scratchy throat

- Mild fever

- Nice 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; conduct more testing, genomic surveillance, and enforce 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.

Scratchy throat seems to be the most common symptom among people infected with Omicron. Doctors in South Africa have now found another symptom: back pain (Daily Post, UK, Dec. 17, 2021).

Transmissibility

All the data generated so far indicate that Omicron is much more transmissible than the Delta. Even though the initial Omicron cases were detected in South Africa only on November 24, 2021, the variant has now spread to over 70 countries in such a short time. India has officially logged over 100 cases now.

There are two things very worrying for Omicron: transmissibility and vaccine escape potential. Omicron seems to be at least four-six times more contagious than Delta. Preliminary data indicates that most current vaccines would have very low efficacy against Omicron.

A new report says that Omicron replicates 70 times faster in bronchial tissues compared to Delta (The Guardian, Dec. 15, 2021).

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 hospitalisations, 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

As explained above, the severity of COVID-19 caused by Omicron seems to be milder than that caused by Delta. However, 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.

However, the WHO has warned against underestimating Omega as causing a 'mild disease. (CNBC, Dec. 15, 2021). According to Dr Maria Van Kerkhove, the elderly, the unvaccinated, and those with underlying health conditions are still at risk of severe disease. People infected with Omicron can show the full spectrum of COVID disease.

As many experts have opined, a small percentage of a huge number is still a big number. Let's say Omicron causes serious disease in just 1 per cent of cases. This amounts to just 1 person in 100 infected cases. As Omicron is estimated to be at least 4-6 times more transmissible than Delta, the cases may surge soon. In just less than 2-3 weeks, Omicron has spread from just 2-3 countries to now over 70. In this time, India's cases have shot up from 0 to over 100 cases now.

So, 1 per cent of 1 lakh is 1,000 people. That is, if there are 1 lakh daily cases, 1,000 people may suffer from severe disease and, at least, 100 may be at the risk of hospitalisations and deaths. If the serious cases occur among co-morbid patients, the chances of hospitalizations and deaths would be very high. This may cause a serious strain on our healthcare systems.

Vaccine Escape Potential

According to a report by Imperial College London (ICL), Omicron largely evades immunity from either past infections or 2 vaccine shots (ICL News, Dec. 17, 2021). The risk of reinfection with Omicron is 5.4 times greater than that with the Delta variant. The protection against reinfection provided by past infection may be as low as 19 per cent.

Vaccine effectiveness against symptomatic Omicron infection is 0-20 per cent after two vaccine doses, and between 55 per cent and 80 per cent after booster shots. This strongly emphasises the need for a booster dose amidst the fast spreading Omicron.

Booster Shots

A very recent report claims that the third dose of the Moderna vaccine enhanced the neutralisation potential of antibodies against both Beta and Omicron variants (News Medical, Dec. 16, 2021)

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 neutralisation 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 3 doses of the vaccine might provide significant protection against Omicron (BBC, Dec. 10. 2021). Many countries, including the 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 the 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 Covishield vaccine provides effective protection (70-75 per cent) against the Omicron variant (The Mint, Dec. 11, 2021).

It is high time that our country approves and administers a third (booster) dose of COVID vaccine (Covaxin/ZyCoV-D/CoviShield/Sputnik or another vaccine) to help prevent a third wave triggered by Omicron or, at least, mitigate its adverse effects!

New COVID Drugs

The new COVID drug, molnupiravir has now been approved in the UK. Thus, the 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.

A more recent report says that Paxlovid is much more effective compared to Molnupiravir.

It is urgently warranted that India soon approves and imports paxlovid and other anti-COVID oral pills which circulate in all states including Manipur to help prevent/mitigate a third wave, or blunt the impacts, in case a third wave emerges!

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 populations with first doses in the next few weeks (4-6 weeks); and targeted vaccinations of all adult populations with second doses in the next 2-3 months.

- Regular and 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.

Debananda S Ningthoujam

Debananda S Ningthoujam

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

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