Coronavirus has traveled to every corner of the world and continuously mutates and changes its character. Research shows that the virus responsible for COVID-19 has the most mutations on the targets of various nucleocapsid gene primers and probes.
8 These changes may affect the virus’s properties. The new variants might have a speedy spreading capacity and cause disease severity. Also, new variants might alter the performance of vaccines, diagnostic tools, therapeutic medicines, and other preventive measures.
9 The capacity of changing variants through genomic changes is one of the main characteristics of this virus. In the waves of the COVID-19 pandemic, the world is suffering from Alpha, Beta, Gamma, Delta variants, and most recently Omicron variants of this virus. WHO designated SARS-CoV-2 variants with Greek alphabet letters according to their characteristics and classified them as variants of concern (VOCs) and variants of interest (VOIs) (
Figure 1). The WHO defined VOCs and VOIs based on the viral genomic changes, transmissibility, neutralization power, detrimental effects, disease presentation, and emerging health risks on the human being.
10 VOCs are refer to variants with increased transmissibility or increased in virulence or decreased in effectiveness available diagnostics, vaccines, therapeutics. Also, VOIs are refer to those variants with genetic changes that are predicted or known to affect virus characteristics and have significant community transmissibility with emerging risk to global public health.
10 The names are given according to the Greek alphabet that may work as a handy short form for the public, the policymakers, and others.
9 Some recently discovered strains are designated as variants under monitoring for further assessment (
Figure 1). This list also includes some former VOIs mutants. The Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), Delta (B.1.617.2), and Omicron (B.1.1.529) are classified as VOCs. On the other hand, Lambda (C.37) and Mu (B.1.621) are enlisted as VOIs (
Table 1).
11 After Alpha, Beta, Gamma, and Delta variants; Omicron another variant named Delta is the latest concern. However, multiple countries discovered the Omicron variant in Noverber 2021 that is the most infectious variant so far.
11 Till now, this Omicron variant has spread more than 150 countries, and it is spreading faster than others.
12 Moreover, WHO classified some variants as variants under monitoring (VUMs) based on the viral genetic changes that might affect virus characteristics. The Pango lineage of designated SARS-CoV-2 VUMs are B.1.1.318, C.1.2, and B.1.640.
11The Alpha variant
B.1.1.7 variant was renamed as Alpha variant on December 18, 2020. The Alpha variant was found in the earliest documented sample that was found in the United Kingdom in September 2020. It is also noted as lineage B.1.1.7.
13 It is defined by 17 mutations, where 14 mutations are because of the change in amino acids. Three others are deletions of 8 mutations in the spike protein gene that help the virus for viral access to the human cell. Viral functions are potentially affected by at least 3 mutations.
14 Research reported the transmissibility of this variant is 43-90% more than the other variants (early SARS-CoV-2 strains) that were existed in the UK previously. The same transmissibility of this variant has been seen in Switzerland, Denmark, and the United States.
15The Alpha variant is associated with increased severity of infection regarding hospitalizations and fatality rates,
16 shows no effect on susceptibility when treating with EUA monoclonal antibody,
17,18 increased transmission.
19 The most common symptoms in infected people by this variant were chills, loss of appetite, headache and muscle aches, etc.
20 According to a survey, sore throat, fever, myalgia, fatigue, cough, found common symptoms of B.1.1.7 infection. However, loss of smell or taste was reported as a less common symptom; and a higher prevalence of having at least one of the symptoms.
21 Graham et al
22 have studied on UK population and reported evidence of persistent cough, fever, diarrhea, delirium, hoarse voice, headache, unusual muscle pains, loss or change in smell or taste, skipped meals, severe shortness of breath, sore throat, chest pain, abdominal pain, and severe fatigue. Moreover, this strain was found to be resistant to neutralization by antibodies. Planas et al. reported increased resistance to neutralizing antibodies by the strains. They found an escape of neutralization occurred due to mutations. B.1.351 variant had shown more resistance than B.1.1.7, and wild type D614G got neutralized easily.
23,24 These escapes from neutralization lead to new complications in the global healthcare system.
The Gamma variant
The Gamma variant was designated on January 11, 2021, by WHO. The earliest documented sample was found in November 2020 in Brazil. It is also known as lineage P.1. This variant has 17 amino acid substitutions, in which 10 are present on the surface as spike protein. All of them, are of particular concern: N501Y, E484K, and K417T. Also, 2 mutations are found; one in its ORF8 region and one in its N region.
30 In 2020, a study among 180 samples identified the lineage P.2 of this virus, where the samples are taken from Rio de Janeiro. By genome sequencing, this P.2 was first identified in October 2020 but appeared in early July 2020.
31 The P.2 case can be asymptomatic in some cases.
32 It has been found higher than expected reinfections with Gamma variant among the Brazilian.
33 This variant involves household transmissions and can be traveled in a community without travel history.
32 As of March 30, 2021, this variant has traveled to 45 countries. Reduced neutralization by MOA therapies, post-vaccination sera, and convalescent sera have attributed this variant. It also showed reduced sensitivity to bamlanivimab and etesevimab when they are used for combined MOA treatment. But this variant shows good sensitivity when treated with some EUA monoclonal antibodies.
17,18The Delta variant
The WHO considers the Delta variant as a VOC. The Delta variant was designated on April 4, 2021, as a VOI and designated on May 11, 2011, as a VOC by the WHO. The earliest documented sample was found in October 2020 in India. It is also recognized as lineage B.1.617.2. In India, it was first acknowledged during an aggressive wave of COVID-19 there in April and May 2021. It is rising so fast than the other variants. Now India is facing big trouble because of this variant. Countries that are linked closely economically to India (eg, countries in East Africa) are probably having a huge risk of affecting by the Delta. Cases with Delta variants in these countries are found among shipping crews at different ports. Again, Delta is the biggest risk for the countries having inadequate access to vaccines, especially the countries in Africa- where most nations can vaccinate less than 5% of their populations. This variant is 60% more transmissible than the Alpha variant that is already known as highly infectious. It can be said that this variant is somewhat resistant to vaccines; more especially in those subjects who have received just a first dose of vaccine.
34 A first vaccine dose of either AstraZeneca’s or BioNTech’s vaccine can reduce the risk by 33% for the Delta variant and 50% for the Alpha variant.
35 This Delta variant showed less sensitivity toward neutralizing antibodies inside the body.
36Another variant has also been identified named as Delta plus. Responsible authorities in India have called it a “VOI,” but WHO hasn’t matched that designation yet. It is also recognized as B.1.617.2.1 or AY.1. It is a sub-lineage of the Delta variant. The difference between these 2 is not so many. For now, only one difference can be known which is an additional mutation in the spike protein found on the surface of the virus. Delta plus shows almost the same transmissibility as the Delta variant. Such mutation has also been found in the Beta and Gamma variants. India’s SARS-CoV-2 Consortium on Genomics reported some attributes of Delta plus variants and that said its binding capacity to the cells of a human lung is stronger and it showed a potential reduction in response while treating with MOA. The response of Delta Plus against a vaccinated body is not still clear to the world.
37By comparing the variants, it can be stated that the Delta variant is the most dangerous variant of this virus so far. Studies say that it has the most effective transmissibility among all other variants. Delta and Delta plus affect the lungs more as they have transmissibility more than others. A big challenge is that patients are coming to hospitals affected by these variants with a worse lung condition in a very short period. It is a matter of hours to get into deadly conditions from an asymptomatic condition. Healthcare facilities are facing a huge challenge to face these cases as they need more high flow oxygen facilities and intensive care units that may not be enough so far. They are facing increased pressure of a patient with a new strong variant against medication, all of a sudden. These variations emerged as an open challenge to individuals as well as the healthcare system.