what is covid 19 and How many COVID variants

Variants of Coronavirus

What Is COVID-19?

COVID-19 is a new strain of coronavirus that has not been previously identified in humans. The COVID-19 is the cause of an outbreak of respiratory illness first detected in Wuhan, Hubei province, China.

Since December 2019, cases have been identified in a growing number of countries. The District’s surveillance data can be found here.

Coronaviruses are a large family of viruses that are known to cause illnesses ranging from the common cold to more severe diseases such as Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS).

What Is a COVID-19 Variant?

Viruses are always changing, and that can cause a new variant, or strain, of a virus to form. A variant usually doesn't affect how the virus works. But sometimes they make it act in different ways.

Scientists around the world are tracking changes in the virus that causes COVID-19. Their research is helping experts understand whether certain COVID-19 variants spread faster than others, how they might affect your health, and how effective different vaccines might be against them.

Currently designated Variants of Concern (VOCs)⁺:

WHO label	Pango   lineage•	GISAID clade	Nextstrain clade	Additional amino acid changes monitored°	Earliest documented   samples	Date of designation
Alpha	B.1.1.7	GRY	20I (V1)	+S:484K +S:452R	United Kingdom,   Sep-2020	18-Dec-2020
Beta	B.1.351	GH/501Y.V2	20H (V2)	+S:L18F	South Africa,   May-2020	18-Dec-2020
Gamma	P.1	GR/501Y.V3	20J (V3)	+S:681H	Brazil,   Nov-2020	11-Jan-2021
Delta	B.1.617.2	G/478K.V1	21A, 21I, 21J	+S:417N +S:484K	India,   Oct-2020	VOI: 4-Apr-2021  VOC: 11-May-2021
Omicron*	B.1.1.529	GR/484A	21K	-	Multiple countries, Nov-2021	VUM: 24-Nov-2021 VOC: 26-Nov-2021

Alpha

Considered a variant of concern by the World Health Organization, alpha was first identified in Kent in the UK in September 2020 and drove the UK’s second wave.

While it was first thought that this variant was around 70% more transmissible than the original (wild-type) SARS-CoV-2 coronavirus, data now suggest that it is 30-40% more transmissible than the original.1

Research has shown vaccine efficacy (two doses) against the alpha variant to be 74.5% with the Oxford-AstraZeneca vaccine, 93.7% with the Pfizer-BioNTech vaccine,2 85.6% with the Novavax vaccine,3 and 100% with the Moderna vaccine.4 A study looking at the Sputnik V vaccine saw some reduced neutralizing activity against the alpha variant,5 and Thailand’s Public Health Ministry has reported that two doses of the Sinovac vaccine are 71-91% effective against alpha.

Beta

First documented in South Africa in May 2020, beta is also considered a variant of concern by WHO.

The US Centers for Disease Control and Prevention (CDC) has linked beta with a 50% increase in transmission,7 but the big worry is the emerging evidence of its ability to evade some of the existing vaccines.

Early studies indicate that the Pfizer vaccine has a slightly lower (72-75%) effectiveness against beta than against the wild-type SARS-CoV-2, but both Pfizer and Moderna say that their vaccines are still 95% effective against severe disease and death. Novavax (60%) and Johnson and Johnson (57%) fare slightly worse. And, while early studies of the Oxford-AstraZeneca vaccine seemed to show low efficacy against beta, real-world data published on 23 July indicated 82% effectiveness in preventing severe disease and death from covid after a single vaccine dose.8

Sputnik V’s maker claims that it is “highly effective” against beta, but at least one study has noted a reduction in neutralizing activity against this variant.5 Data on the efficacy of Sinovac’s CoronaVac are lacking, although reports from Hong Kong suggested that the level of protection was 70% lower against beta than against wild-type.9

Gamma

Gamma was first identified in Manaus, Brazil, in November 2020 and is another variant of concern for WHO. At the time of writing, it remains the dominant variant in South America.10

Research suggests that gamma is 1.7-2.4 times more transmissible than wild-type SARS-CoV-2.11

Few studies have been conducted to determine the efficacy of covid vaccines against the gamma variant. However, a report looking at an outbreak of gamma among employees of a goldmine in French Guiana noted a “strikingly high attack rate” among people fully vaccinated with the Pfizer vaccine, as 60% of the fully vaccinated people became infected, compared with 75% of unvaccinated miners without a history of infection. The manufacturers of Sputnik V claim that it is “highly effective” against variants including gamma, but a study published in July looking at antibody responses found reduced neutralizing activity against gamma and other variants.13

Delta

A WHO variant of concern now dominant in Europe and the US, delta continues to drive a steep rise in cases throughout much of Asia including Bangladesh, Iran, Iraq, Japan, Kazakhstan, Malaysia, Myanmar, Pakistan, South Korea, Thailand, and Vietnam,14 as well as in India, where it was first identified in October 2020.

Delta is the most transmissible form of SARS-CoV-2 detected so far: as much as 60% more so than the alpha variant, one study estimated. Researchers have described it as an “improved” version of the alpha variant thanks to a mutation that makes it more infective in the airways. This means an increased amount of virus in the infected person such that they may expel more virus into the air, and one preprint study concluded that infected individuals had viral loads as much as 1260 times higher than people infected with wild-type SARS-CoV-2. Another concern is that if the delta variant is better at infecting human airway cells people may become infected after lower exposure.

The data so far are positive regarding existing vaccines: research suggests vaccine efficacy of 67% with the Oxford-AstraZeneca vaccine and 88% with the Pfizer-BioNTech vaccine against delta, while the manufacturers of Sputnik V claim that it is 90% effective against it.

Omicron

On 26 November 2021, WHO designated the variant B.1.1.529 a variant of concern, named Omicron, on the advice of WHO’s Technical Advisory Group on Virus Evolution (TAG-VE).  This decision was based on the evidence presented to the TAG-VE that Omicron has several mutations that may have an impact on how it behaves, for example, on how easily it spreads or the severity of illness it causes. Here is a summary of what is currently known.  

Current knowledge about Omicron 

Researchers in South Africa and around the world are conducting studies to better understand many aspects of Omicron and will continue to share the findings of these studies as they become available.  

Transmissibility: It is not yet clear whether Omicron is more transmissible (e.g., more easily spread from person to person) compared to other variants, including Delta. The number of people testing positive has risen in areas of South Africa affected by this variant, but epidemiologic studies are underway to understand if it is because of Omicron or other factors.  

The severity of disease: It is not yet clear whether infection with Omicron causes more severe disease compared to infections with other variants, including Delta.  Preliminary data suggests that there are increasing rates of hospitalization in South Africa, but this may be due to increasing overall numbers of people becoming infected, rather than a result of a specific infection with Omicron.  There is currently no information to suggest that symptoms associated with Omicron are different from those from other variants.  Initially reported infections were among university students—younger individuals who tend to have the more mild disease—but understanding the level of severity of the Omicron variant will take days to several weeks.  All variants of COVID-19, including the Delta variant that is dominant worldwide, can cause severe disease or death, in particular for the most vulnerable people, and thus prevention is always key. 

 

Effectiveness of prior SARS-CoV-2 infection 

Preliminary evidence suggests there may be an increased risk of reinfection with Omicron (ie, people who have previously had COVID-19 could become reinfected more easily with Omicron), as compared to other variants of concern, but the information is limited. More information on this will become available in the coming days and weeks. 

Effectiveness of vaccines: WHO is working with technical partners to understand the potential impact of this variant on our existing countermeasures, including vaccines. Vaccines remain critical to reducing severe disease and death, including against the dominant circulating variant, Delta. Current vaccines remain effective against severe disease and death.   

Effectiveness of current tests: The widely used PCR tests continue to detect infection, including infection with Omicron, as we have seen with other variants as well. Studies are ongoing to determine whether there is any impact on other types of tests, including rapid antigen detection tests.  

Effectiveness of current treatments:   Corticosteroids and IL6 Receptor Blockers will still be effective for managing patients with severe COVID-19. Other treatments will be assessed to see if they are still as effective given the changes to parts of the virus in the Omicron variant.  

 

Studies underway 

At the present time, WHO is coordinating with a large number of researchers around the world to better understand Omicron. Studies currently underway or underway shortly include assessments of transmissibility, the severity of infection (including symptoms), the performance of vaccines and diagnostic tests, and the effectiveness of treatments.    

WHO encourages countries to contribute to the collection and sharing of hospitalized patient data through the WHO COVID-19 Clinical Data Platform to rapidly describe clinical characteristics and patient outcomes.  

More information will emerge in the coming days and weeks. WHO’s TAG-VE will continue to monitor and evaluate the data as it becomes available and assess how mutations in Omicron alter the behavior of the virus.  

 

Recommended actions for countries 

As Omicron has been designated a Variant of Concern, there are several actions WHO recommends countries to undertake, including enhancing surveillance and sequencing of cases;  sharing genome sequences on publicly available databases, such as GISAID; reporting initial cases or clusters to WHO; performing field investigations and laboratory assessments to better understand if Omicron has different transmission or disease characteristics, or impacts the effectiveness of vaccines, therapeutics, diagnostics or public health and social measures.  More detail in the announcement from 26 November.  

Countries should continue to implement effective public health measures to reduce COVID-19 circulation overall, using risk analysis and a science-based approach. They should increase some public health and medical capacities to manage an increase in cases.  WHO is providing countries with support and guidance for both readiness and response.  

In addition, it is vitally important that inequities in access to COVID-19 vaccines are urgently addressed to ensure that vulnerable groups everywhere, including health workers and older persons, receive their first and second doses, alongside equitable access to treatment and diagnostics.  

 

Recommended actions for people 

The most effective steps individuals can take to reduce the spread of the COVID-19 virus is to keep a physical distance of at least 1 meter from others; wear a well-fitting mask; open windows to improve ventilation; avoid poorly ventilated or crowded spaces; keep hands clean; cough or sneeze into a bent elbow or tissue, and get vaccinated when it’s their turn.  

WHO will continue to provide updates as more information becomes available, including following meetings of the TAG-VE. In addition, information will be available on WHO’s digital and social media platforms. 

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