The omicron variant is the most serious hazard since the outbreak began.
 |
| [Corona Virus details] |
COVID-19 has been rampaging over the world for two years and shows no signs of abating, whereas the Wuhan coronavirus has mutated multiple times in order to adapt to the human body. Despite the fact that scientists and researchers have learnt a great deal about the virus and devised techniques of treatment and prevention of infection that have saved countless lives, the race between the virus and scientists continues.
According to WHO experts, the future of the COVID-19 pandemic is questionable based on the current scenario with coronavirus transmission. Scientists are investigating numerous hypotheses, one of which is that the omicron version of SARS-CoV-2, with its reduced pathogenicity, is a sign that COVID-19 would progressively evolve into a seasonal cold virus. However, the pandemic is still in full force and will not abate until vaccination coverage reaches at least 70% of the world's population. Even in this event, the Wuhan coronavirus would not go completely, but will instead become an endemic infection, causing local outbreaks similar to traditional ARVI.
Dominant strains
By the end of 2021, the number of COVID-19 cases has nearly tripled to nearly 300 million, with a 5.4 million death toll that continues to rise. During this period, the delta version of the SARS-CoV-2 coronavirus, discovered in India in December 2020, has spread around the world. By November of this year, it had been identified in 179 nations as the dominant strain that had overtaken the earlier varieties. This was made possible by mutations in the genes encoding the spike protein (S-protein). The S-protein binds with the ACE2 receptor on the surface of human cells, allowing the virus to enter the cell. Changes in the S-protein impact not just the virus's transmissibility, but also its neutralization by antibodies.
SARS-CoV-2 delta is thought to be the most contagious of the respiratory viruses. It is 40-60% more infectious than the alpha strain (British strain) and 225% more infectious than the original strain. The Coronavirus reproduction index (the average number of individuals infected by one sick person) increased from 2.4-2.6 to 5-9. In comparison, the reproduction indices of the following viral illnesses are: 0.2-0.8 (MERS), 1.2-1.4 (seasonal flu), 1.4-1.8 (Ebola virus), 2-4 (colds diseases and seasonal SARS), 3.5-6 (smallpox), and 10-12 (rabies) (chickenpox). According to data provided by Chinese scientists, those infected with the delta variation had a thousand times more copies of the virus in their respiratory tracts than people infected with other strains of the Coronavirus.
Although delta has been identified as a cause for concern because to its increased tolerance to neutralizing antibodies, immunity maintained after recovery from alpha Coronavirus or established through vaccination remains beneficial in avoiding severe COVID-19 or hospitalization. According to certain research, vaccinated persons with a confirmed COVID-19 diagnosis have a lower viral load on average. Although not all doctors have proved this, these people are infectious for a shorter amount of time.
The delta variation, commonly known as the Indian strain, is to blame for India's catastrophic second wave of the Coronavirus epidemic, which began in February 2021. The tsunami subsequently extended to other nations, including Fiji, the United Kingdom, and South Africa, before reaching the rest of the world. This has resulted in an increase in morbidity, mortality, and new illnesses that arise despite vaccination. Some health experts have raised worry that the new strain might make herd immunity hard to establish since it may be transferred among vaccinated people. Nonetheless, studies have indicated that vaccinating the whole population will drastically reduce the virus's development and bring the pandemic to a halt.
Early study revealed that the Coronavirus's delta form caused more severe COVID-19 than other variants. Patients infected with the delta version are more likely to develop pneumonia or need an oxygen mask than those infected with the classic or alpha type. At the same period, the risk of being admitted to a hospital has more than doubled, the chance of being admitted to an intensive care unit has climbed by 287 percent, and the risk of mortality has increased by 137 percent.
The African mutant
The novel omicron version of SARS-CoV-2, discovered in South Africa, was identified on November 24, 2021, and the WHO declared it as a cause for concern two days later. This strain has a disproportionately high number of mutations. It possesses 60 more mutations than the conventional Wuhan strain, with 32 of them affecting the S-protein. Many genomic modifications do not occur in other variations.
Despite accusations that the omicron was created artificially, the quantity of mutations may be explained by the fact that the virus developed for a long period in the patient's body, which has a considerably compromised immune system. In this context, experts believe that its emergence is linked to HIV infection in a SARS-CoV-2 infected patient. Furthermore, because viruses interchange genetic material, one of the changes might have come from the HCoV-229E coronavirus, which causes the common cold.
Patients with the omicron strain are said to be 50 to 70% less likely to be hospitalized than those with the delta strain. Although Omicron-variant viruses propagate 70 times quicker in bronchial tissues than prior strains, it is hypothesized that they do not penetrate deeper into the lungs and are less likely to cause pneumonia and acute respiratory distress syndrome.
Despite indications that omicron produces less illness, it is more transmissible, evades the immune system, and is more vaccine resistant. Even though this strain is milder than the delta version, it can place a significant load on the healthcare system by increasing hospitalizations owing to increased infections. The omicron variety had been detected in more than 80 nations on all continents except Antarctica by the end of 2021. It is actively replacing the delta strain and will most likely be the prevalent type of SARS-CoV-2 by 2022.
According to health specialists and officials, the omicron variant is the most serious hazard since the outbreak began. However, according to the most recent evidence, booster doses of vaccinations are capable of restoring the body's defenses to levels characteristic of alpha and other coronavirus strains (about 80 percent).
Difficulty with vaccines
In March 2021, scientists were confronted with unexpected and unusual problems as a result of some vaccinations, manifesting as blood clotting issues. These vaccines, manufactured by Oxford-AstraZeneca and Johnson & Johnson, are based on adenoviruses, and physicians have discovered a possible relationship to thrombosis. Vaccines were first assumed to have no effect on thrombosis, but investigations have revealed a direct association between the two. Vaccine use in various countries has been halted pending further explanation of potential consequences.
The ChAdOx1 viral vector served as the foundation for the Oxford-AstraZeneca Vaxzevria vaccine, while the HAdV-D26 adenovirus-based vector served as the foundation for the Johnson & Johnson vaccine. A very tiny proportion of people who received one of these vaccinations experienced a potentially fatal bleeding disease known as thrombosis with thrombocytopenia syndrome (TTS).
Scientists uncovered the likely mechanism of problems in December 2021. It involves adenovirus attaching to platelet factor 4 (or antiheparin factor, PF4), which sets off a chain reaction that results in the production of blood clots. The adenovirus adheres to PF4 after injection, but in extremely rare circumstances it reaches the circulation, where it, together with PF4, induces the immune system to respond, mistaking both molecules for foreign.
Antibodies against the antiheparin factor are produced as a result of an improper immunological response. These antibodies then link to platelets, causing them to clump and form blood clots. This occurs in exceedingly uncommon circumstances, and doctors highlight that the advantages and safety of adenovirus vaccinations outweigh the possible concerns.
A blow to the body
The SARS-CoV-2 coronavirus is distinct from other respiratory viruses in that it may infect the body systemically, causing immune system failure and disrupting the activities of many tissues and organs. Identifying the processes is required to avoid the severe course of COVID-19; however, specialists do not yet understand all of the nuances of such an impact. Immune failure, for example, manifests itself not just as a cytokine storm, but also as lymphopenia, or a reduction in the number of lymphocytes battling the infection.The SARS-CoV-2 coronavirus is distinct from other respiratory viruses in that it may infect the body systemically, causing immune system failure and disrupting the activities of many tissues and organs. Identifying the processes is required to avoid the severe course of COVID-19; however, specialists do not yet understand all of the nuances of such an impact. Immune failure, for example, manifests itself not just as a cytokine storm, but also as lymphopenia, or a reduction in the number of lymphocytes battling the infection.
The infection frequently causes neurological issues, which are found in around 84 percent of patients. Ill patients frequently describe a loss of taste and smell, and others have muddled cognition. There have also been reports of strokes, convulsions, and even mental issues. This was initially explained by the fact that SARS-CoV-2 destroys nerve cells, but later researchers refuted the virus's supposed neurotropicity. It was discovered that it does not directly impact nerve cells, as evidenced by studies on lymphocytes. That is, the loss of smell is not caused by the virus infiltrating the cells of the olfactory bulb.
Researchers discovered that the Coronavirus infects endotheliocytes, which line the blood-brain barrier arteries. This causes cell death and vascular damage. As a result, the blood flow to the brain is reduced, and oxygen and glucose deficiency ensues.
Scientists are actively investigating the omicron version to understand how badly it might impair COVID-19 acquired immunity and the overall epidemiological condition. Despite the fact that many experts believe the omicron version produces a milder COVID-19, any forecasts should be made with extreme caution, and all efforts and measures should be concentrated toward SARS-CoV-2 prevention and the development of novel therapies.
—The author MD Mahmud Hasan is a student at Department of Criminology, University Of Dhaka in Bangladesh.