From Delta to Omicron: All about Covid-19 and its many variants

Ever since Covid-19 hit the world in November 2019, the changes that the virus — declared a pandemic in March 2020 — brought, have been drastic and significant, prompting the world to look at quick vaccination options alongside precautionary measures.

All viruses, including SARS-CoV-2 — that causes Covid-19 — change over time, a phenomenon known as mutation. A virus with one or more new mutations is referred to as a ‘variant’ of the original virus, according to the World Health Organization (WHO). “Most changes have little to no impact on the virus’ properties. However, some changes may affect the virus’ properties, such as how easily it spreads, the associated disease severity, or the performance of vaccines, therapeutic medicines, diagnostic tools, or other public health and social measures,” mentions WHO on its website.

Here’s your ready reckoner on Covid-19 and its long list of variants.



Per WHO, the virus that causes Covid-19 and the one that caused the outbreak of Severe Acute Respiratory Syndrome (SARS) in 2003 are related to each other genetically, but the diseases they cause are quite different. SARS was more serious but much less infectious than Covid-19. There have been no outbreaks of SARS anywhere in the world since 2003.


WHO says most people infected will experience mild to moderate respiratory illness and recover without requiring special treatment. Older people, and those with underlying medical problems like cardiovascular disease, diabetes, chronic respiratory disease, and cancer, are more likely to develop serious illnesses.

According to International Diabetes Federation, “When people with diabetes develop a viral infection, it can be harder to treat due to fluctuations in blood glucose levels and, possibly, the presence of diabetes complications…Firstly, the immune system is compromised, making it harder to fight the virus and likely leading to a longer recovery period. Secondly, the virus may thrive in an environment of elevated blood glucose.”


People with Covid have had a wide range of symptoms reported – ranging from mild symptoms to severe illness, as per Centers for Disease Control and Prevention (CDC). Symptoms may appear 2-14 days after exposure to the virus. Anyone can have mild to severe symptoms. People with these symptoms may have Covid:

– Fever or chills
– Cough
– Shortness of breath or difficulty breathing
– Fatigue
– Muscle or body aches
– Headache
– New loss of taste or smell
– Sore throat
– Congestion or runny nose
– Nausea or vomiting
– Diarrhea

CDC also stated that the list is not exhaustive. “Older adults and people who have severe underlying medical conditions like heart or lung disease or diabetes seem to be at higher risk for developing more serious complications from Covid-19 illness,” it says on its website.

When is it an emergency?

As per CDC, the warning signs include:

*Trouble breathing
*Persistent pain or pressure in the chest
*New confusion
*Inability to wake or stay awake
*Pale, gray, or blue-coloured skin, lips, or nail beds, depending on skin tone

“This list is not all possible symptoms. Please call your medical provider for any other symptoms that are severe or concerning to you,” it states.


The Covid-19 virus spreads primarily through droplets of saliva or discharge from the nose when an infected person coughs or sneezes, as per WHO. Which is why, it’s extremely important to practise respiratory etiquette (for example, coughing into a flexed elbow).

A health worker administers Covid-19 vaccine at a BMC run vaccination centre in Chembur, Mumbai. (Source: Express Photo by Amit Chakravarty)

Vaccine effectiveness

All Covid-19 vaccines approved by WHO for emergency use listing have been through randomised clinical trials to test their quality, safety and efficacy, states WHO. “Covid-19 vaccines are crucial tools in the pandemic response and protect against severe disease and death. Vaccines provide at least some protection from infection and transmission, but not as much as the protection they provide against serious illness and death,” WHO reads.


Genomic variants of various viruses are a natural phenomenon and are found in almost all countries, as per a Press Information Bureau report detailing The Indian SARS-CoV-2 Consortium on Genomics (INSACOG)’s (a grouping of 10 National Laboratories established by Ministry of Health and Family Welfare, Government of India) analysis of circulating Covid-19 viruses.

According to CDC, which developed a variant classification, there are three major categories:

*Variant of interest (VOIs)
*Variant of concern (VOCs)
*Variant of high consequence

CDC states a ‘variant of concern’ is one for which there is evidence of an increase in transmissibility, more severe diseases that require hospitalisation or death, a significant reduction in neutralisation by antibodies generated during previous infection or vaccination, reduced effectiveness of treatments or vaccines, or diagnostic detection failures.

‘Variants of concern’ include B.1.1.7 or Alpha first identified in the UK, B.1.351 or Beta first identified in South Africa, and B.1.427 or Epsilon first identified in the US. Earlier, WHO had identified the Delta variant or B.1.617.2, first found in India, as a ‘variant of concern’.

As per WHO, when necessary, variants not otherwise meeting all criteria outlined in the definitions may be designated as VOCs/VOIs/VUMs (variants under monitoring), and those posing a diminishing risk relative to other circulating variants may be reclassified, in consultation with the Technical Advisory Group on Virus Evolution (formally called the Virus Evolution Working Group).

Why do variants occur?

Variants are normal part of evolution and as long as the virus is able to infect, replicate and transmit, they will continue to evolve.

Are all variants equally infectious?

As per MoHFW, not all variants are dangerous and most often than not, we don’t notice them. “Only when they are more infectious, or can re-infect people, do they gain prominence. The most important step to avoid generation of variants is to reduce the number of infections,” it reads.

Vaccine effectiveness against variants

As per WHO, data continues to be collected and analysed on new variants of the Covid-19 virus. “The Covid-19 vaccines that are currently in development or have been approved are expected to provide at least some protection against new virus variants because these vaccines elicit a broad immune response involving a range of antibodies and cells. Therefore, changes or mutations in the virus should not make vaccines completely ineffective. In the event that any of these vaccines prove to be less effective against one or more variants, it will be possible to change the composition of the vaccines to protect against these variants,” reads WHO.

Mu (B.1.621)

Origin: The Mu variant was first reported in the US in January 2021, although cases only numbered in the single digits.

Severity: Mu’s severity was unknown as it affected very less people.

Transmission: Although the WHO continues to classify Mu as a ‘variant of interest’ globally, the CDC lists Mu simply as a ‘variant being monitored’. The CDC counts 10 variants in the variant being monitored group, including three once considered variants of concern: the Alpha, Beta, and Gamma strains.

Lambda (C.37)

Origin: It was first documented in Peru in December 2020.

Severity: According to data from the GISAID COVID tracking initiative, there were nine cases globally that were associated with Lambda. Of these, three were in Chile and six in Argentina, reported in a September 2021 article.

Symptoms: The main symptoms, according to the NHS, are a high temperature, a new, continuous cough, and a loss or change to your sense of smell or taste.

Transmission: It is on the list of classified variants of interest of WHO. As per WHO, as a variant of interest, the WHO considers Lambda to have mutations with established, or suspected, implications for its transmissibility and severity, and has been detected in multiple countries.

Vaccine effectiveness: In a pre-print paper that has was not peer-reviewed, researchers found that mRNA vaccines were effective against the Lambda variant. The results of this paper suggested that vaccines in current use will remain protective against the Lambda variant.

Delta (B.1.617.2)

Origin: The Delta variant, or B.1.617.2, has been largely responsible for driving the second wave of coronavirus infections, and was first identified in India. It has since mutated into the variants AY.1 and AY.2.

Severity: As per Mayo Clinic and CDC, Delta variant is nearly twice as contagious as earlier variants and might cause more severe illness. “It caused more serious disease than the original virus, resulting in hospitalisations in large numbers, and also had higher rates of complications, increased number of deaths,” Dr Monalisa Sahu, consultant infectious diseases, Yashoda hospitals Hyderabad told

Symptoms: Individuals with Delta variant have fever, cough, loss of taste, smell, and extreme tiredness. Sore throat, headache and diarrhea are less common, mentioned Dr Sahu.

Transmission: The greatest risk of transmission is among unvaccinated people, as per Mayo Clinic. People who are fully vaccinated can get vaccine breakthrough infections and spread the virus to others. However, it appears that vaccinated people spread Covid-19 for a shorter period than do unvaccinated people.

Vaccine effectiveness: A recently published study (conducted by several Indian scientists and those from the Cambridge Institute of Therapeutic Immunology and Infectious Disease) found that the Delta variant is eight times less sensitive to antibodies generated from Covid vaccines. It has been seen that both vaccines available in India have good protection against the delta variant. While the protection from symptomatic infection is around 70 per cent, protection from severe infections hospitalisation and death are over 95 per cent, Dr Trupti Gilada, consultant physician in infectious diseases, Masina Hospital told in an earlier interview.

covid variants The most accepted and commonly used method of diagnostic for SARS-CoV2 Variant is RT-PCR method (Source: Express Photo by Amit Chakravarty)

Delta Plus

Origin: The sub-lineages AY.1 and AY.2 of Delta are called Delta Plus. Delta Plus formed as a result of Delta acquiring a mutation called K417N in the spike protein. While the WHO lists Delta as a variant of concern, the Indian government has classified Delta Plus (AY.1) as a variant of concern in the country. This mutant of Delta was first detected in Europe in March 2021, but it came to light on June 13, 2021.

Severity: “The Delta variant, first detected in India, eventually became a huge problem for the whole world. However, the Delta Plus variant, at present, is limited to smaller areas in the country,” said Dr Shuchin Bajaj, internal medicine, founder-director, Ujala Cygnus Group of Hospitals.

The Delta Plus variant spreads at almost 60 per cent faster rate than its predecessor Delta variant, binds more easily to lung cells and enters the cells more efficiently. It also has higher resistance to the drugs used against Covid-19, explained Dr Sahu.

Symptoms: According to ZOE Covid study app in the UK, people reported symptoms like headaches, sore throats, runny noses, and fever. “Its symptoms are that of Delta as well as that of Beta, which include cough, diarrhea, fever, head ache, skin rash, discoloration of fingers and toes. Other symptoms attributed to Delta Plus include, pain in abdomen, nausea, and loss of appetite,” Dr Sahu added.

Transmission: In the case of the Delta Plus variant, the Health Ministry identified three characteristics — increased transmissibility; stronger binding in receptors of lung cells; and potential reduction in monoclonal antibody response

Vaccine effectiveness: Rajesh Bhushan, Union Health Ministry Secretary says that both Indian vaccines — Covishield and Covaxin are effective against the Delta variant,

Omicron (B.1.1.529)

Origin: It is a new variant of SARS-CoV-2 that has recently been reported from South Africa on November 24, 2021 called as B.1.1.529 or Omicron (based on Greek alphabets like alpha, beta, delta etc). According to Ministry of Health and Family Welfare (MoHFW)’s FAQs on SARS-CoV-2 Variant-Omicron, this variant has shown a very large number of mutations, especially more than 30 on the viral spike protein, which is the key target of the immune response.

Severity: As per Mayo Clinic, it’s not yet clear if Omicron causes more severe disease. “The variant is seen to be attacking the younger population more,” said Dr Abhishek Subhash, Consultant Internal Medicine at Bhatia Hospital. However, CDC mentions that due to the small number of cases, “the current severity of illness and death associated with this variant is unclear”.

Symptoms: As per Dr Sahu, the symptoms more commonly seen in individuals with Omicron include body aches, extreme tiredness, scratchy throat, dry cough and headache. Some individuals have high grade fever as well.

We are seeing milder symptoms with Omicron patients till now, said Dr Abhishek. “The symptoms are mostly the same as the common cold and flu. Fever last only for two-three days and there is no decrease in oxygen levels this time in Omicron patients,” he told However, the patients haven’t reported loss of smell and taste in most conditions.

Diagnosis: The most accepted and commonly used method of diagnostic for SARS-CoV2 Variant is RT-PCR method. This method detects specific genes in the virus, such as Spike (S), Enveloped (E) and Nucleocapsid (N) etc to confirm the presence of virus. “However, in case of Omicron, as the S gene is heavily mutated, some of the primers may lead to results indicating absence of the S gene (called as S gene drop out). This particular S gene drop out along with the detection of other viral genes could be used a diagnostic feature of Omicron. However, for final confirmation of the omicron variant genomic sequencing is required, India’s MoHFW states.

Transmission: This variant might spread more easily than other variants, including Delta. As per Dr Sahu, Omicron is highly transmissible, being about 1.6 times more transmissible than Delta. “It has properties of immune evasion offered by previous infections with other variants of Covid-19. There is also higher chance of community spread with Omicron variant,” Dr Sahu told

It’s expected that people who are fully vaccinated likely can get breakthrough infections and spread the virus to others. However, the Covid-19 vaccines are expected to be effective at preventing severe illness. This variant also reduces the effectiveness of some monoclonal antibody treatments, as per Mayo Clinic.

However, Dr Gowri Kulkarni, Head of Medical Operations, MediBuddy warned that though the Omicron variant is showing much milder symptoms, especially in vaccinated people, “it is spreading very fast”. “If volumes rise exponentially as we are seeing, it will definitely stress the healthcare system and infrastructure and affect the most vulnerable – older individuals, unvaccinated population and people with comorbidities. The peak is most likely to hit by mid-February considering that omicron will be the most prevalent variant and having seen its transmissibility higher than Delta. The government imposing restrictions much earlier than we are hoping could help reduce the total numbers. We cannot be complacent. Please get yourself vaccinated as soon as you can if you are eligible for it,” Dr Kulkarni said.

Vaccine effectiveness: Early evidence suggests that fully vaccinated people who become infected with the Omicron variant can spread the virus to others, as per CDC. “All FDA-approved or authorised vaccines are expected to be effective against severe illness, hospitalisations, and deaths. The recent emergence of the Omicron variant further emphasises the importance of vaccination and boosters,” it reads.

The vaccines are likely to provide some protection against severe illness, hospitalisations and death; a booster dose of vaccine could help further, said Dr Sahu.

Other variants

As per Mayo Clinic, The alpha, gamma and beta variants continue to be monitored but are spreading at “much lower levels in the US”. The American academic medical center states that the mu variant is also being monitored.

How are Delta and Omicron different? Can someone be affected by both at the same time?

The distinguishing characteristic in Omicron is that there is absence of breathing difficulty in compared to the Delta strain where even the patients in the ward were requiring oxygen support, Dr Abhishek asserted.

“It is important to note that the Delta strain is still there and people could be infected with both these strains. So, symptoms will vary accordingly,” Dr Abhishek mentioned.

IHU Variant (B.1.640.2)


Scientists in France have identified a new strain of coronavirus with more mutations than the Omicron variant. The cases have been linked to travel to the African country Cameroon. Dr Sahu said that the variant has 46 mutations and 37 deletions, resulting in 30 amino acid substitutions and 12 deletions. “This variant has not yet been classified as variant of concern or variant under investigation by the WHO. Twelve cases of this variant have been reported from France,” she said.


“There are scores of new variants discovered all the time, but it does not necessarily mean they will be more dangerous. What makes a variant more well-known and dangerous is its ability to multiply because of the number of mutations it has in relation to the original virus,” said epidemiologist Eric Feigl-Ding in a post on Twitter.


Feigl-Ding said, “I doubt it will win over Omicron (5-6x faster than Delta) or Delta (which is 2x faster than original).”

Vaccine effectiveness

The researchers of the study at Marseille-based Mediterranee Infection University Hospital Institute found that it also carries the E484K mutation, which could mean that the variant will be more resistant to vaccines.

Health experts urge that if people want to get back to normal, a significant portion of the population needs to be vaccinated, reported UC Davis Health. As long as a chunk of people across the world are unvaccinated, new strains of the virus will continue to develop and cause problems.

As per CDC, new variants of the virus are expected to occur.

*Taking steps to reduce the spread of infection, including getting a Covid-19 vaccine, are the best way to slow the emergence of new variants.
*It states that vaccines reduce your risk of severe illness, hospitalisation, and death from Covid-19.

Dr Bajaj said, vaccine breakthroughs or getting infected even after vaccination will continue to happen but the severity of infection will reduce. “Please go and get yourself vaccinated so that you don’t need to go to the hospital in the next wave,” he said.

To prevent infection and slow its transmission, WHO recommends the following

*Wash your hands regularly with soap and water, or clean them with alcohol-based hand rub.
*Maintain at least one metre distance between you and people coughing or sneezing.
*Avoid touching your face.
*Cover your mouth and nose when coughing or sneezing. However, WHO advises rational use of medical masks to avoid unnecessary wastage of precious resources and misuse of masks.
*Stay home if you feel unwell.
*Refrain from smoking and other activities that weaken the lungs.
*Practice physical distancing by avoiding unnecessary travel and staying away from large groups of people.

Role of masks

As per, wearing a mask is an effective way to reduce the spread of earlier forms of the virus, the Delta variant and other known variants.

*People who are not fully vaccinated should take steps to protect themselves, including wearing a mask indoors in public at all levels of community transmission.
*People who are fully vaccinated should wear a mask indoors in areas of substantial or high transmission.
*Wearing a mask is very important if you or someone in your household
*Has a weakened immune system
*Has an underlying medical condition
*Is an older adult
*Is not fully vaccinated

📣 For more lifestyle news, follow us on Instagram | Twitter | Facebook and don’t miss out on the latest updates!

Source link