Alpha-variant covid-19 (B.1.1.7)

Viruses make carbon copies of themselves to reproduce but they aren't perfect at it. Errors can creep in that change the genetic blueprint, resulting in a new version of the virus - in other words, a variant.

The Alpha variant of SARS-CoV-2 evolved mutations that allowed it to more efficiently suppress the immune system’s early response to infection.

The variant known as alpha or B.1.1.7 or 201/501Y.V1 was first documented in the United Kingdom in September 2020, it spread rapidly around the world, suggesting it was significantly more transmissible than the original virus. It became the dominant variant in the U.S., where the CDC classified it as a variant of concern.

The variant has shown 30-50% enhanced transmissibility compared to initially merged SARS-CoV-2. It contains several key mutations in the spike protein – the key the virus uses to gain entry to human cells – that mark it out from the original Wuhan strain. One is a N501Y mutation, which improves spike protein binding to cellular receptors making the virus more contagious.

In the U.S., in mid-April 2020—before Delta became predominant—Alpha comprised 66% of cases.

Studies have suggested the B.1.1.7 lineage is more likely to land infected people in the hospital and is deadlier than the original virus.
Alpha-variant covid-19 (B.1.1.7)

Delta variant Covid-19

The B.1.617.2 (Delta) variant of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes coronavirus disease 2019 (Covid-19) has now been detected across the globe.

The Delta variant (B.1.617.2, formerly India variant) of SARS-CoV-2 originated and rapidly spread in India, and is emerging in the United States, as well as in many other countries. On June 15, 2021, the CDC designated the Delta variant a variant of concern (VOC) in the United States.

Variants of SARS-CoV-2 continue to emerge. The Delta variant is highly transmissible. Data indicate that Delta is 40-60% more transmissible than Alpha and almost twice as transmissible as the original Wuhan strain of SARS-CoV-2.

The Delta variant of SARS-CoV-2 is highly transmissible; vaccination is the most important strategy to prevent severe illness and death. On July 27, CDC recommended that all persons, including those who are fully vaccinated, should wear masks in indoor public settings in areas where COVID-19 transmission is high or substantial.

The delta variant is characterized by the spike protein mutations T19R, Δ157-158, L452R, T478K, D614G, P681R, and D950N. Several of these mutations may affect immune responses directed toward the key antigenic regions of receptor binding protein (452 and 478) and deletion of part of the N-terminal domain.

P681R is at the S1–S2 cleavage site, and it appears that strains with mutations at that site may have increased replication, which leads to higher viral loads and increased transmission.

Symptoms of Delta tend to be a little different than other strains, but that does not necessarily mean the associated symptoms are more severe.
Delta variant Covid-19

Coronavirus disease

Coronaviruses are a group of viruses belonging to the family of Coronaviridae, which infect both animals and humans. Coronavirus (COVID-19) is an illness caused by a virus that can spread from person to person. The virus that causes COVID-19 is a new coronavirus that has spread throughout the world.

This pandemic (caused by the virus SARS-CoV-2) is the greatest threat not only to global health but also has far-reaching socio-economic impact on nearly all the countries in the world.

The first cases of coronaviruses in human found in 1965 by Tyrrell and Bynoe. They observed that they could passage a virus named B814. It was observed in human embryonic tracheal organ cultures obtained from the respiratory tract of an adult with a common cold symptom. The first 4 cases of COVID-19 were first reported on the 29th December 2019, all linked to Huanan (Southern China) seafood wholesale market. Many of the initial patients were either stall owners, market employees, or regular visitors to this market. Environmental samples taken from this market in December 2019 tested positive for SARS-CoV-2, further suggesting that the market in Wuhan City was the source of this outbreak or played a role in the initial amplification of the outbreak.

Another coronavirus, SARS-CoV-1, the cause of the Severe Acute Respiratory Syndrome (SARS) outbreak in 2003, was also closely related to other coronaviruses isolated from bats. These close genetic relations of SARS-CoV-1, SARSCoV-2 and other coronaviruses, suggest that they all have their ecological origin in bat populations.

Signs and symptoms include respiratory symptoms and include fever, cough and shortness of breath. In more severe cases, infection can cause pneumonia, severe acute respiratory syndrome and sometimes death.

Standard recommendations to prevent the spread of COVID-19 include frequent cleaning of hands using alcohol-based hand rub or soap and water; covering the nose and mouth with a flexed elbow or disposable tissue when coughing and sneezing; and avoiding close contact with anyone that has a fever and cough.
Coronavirus disease