•According to the WHO, most changes have little to no impact on the virus’ properties.
•As of December 2021, five VOCs had been recognized by WHO; Alpha, Beta, Gamma, Delta and Omicron.
Image: REUTERS
A variant is a slightly altered or mutated version of a virus. The Covid-19 virus like any other has changed over time.
According to the WHO, most changes have little to no impact on the virus’ properties.
However, some changes may affect the virus’s 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.
WHO, in collaboration with researchers have been monitoring the evolution of SARS-CoV-2 since January 2020.
They categorised the emergence of variants according to the risks they held to global public health.
The specifications are Variants of Interest (VOIs) and Variants of Concern (VOCs) which were arrived at in order to prioritise global monitoring and research, and ultimately to inform the ongoing response to the pandemic.
WHO and its international networks have set up systems that detect “signals” of potential VOIs or VOCs and assess these based on the risk posed to global public health.
Reducing transmission through established and proven disease control methods/measures, as well as avoiding introductions into animal populations, are crucial aspects of the global strategy to reduce the occurrence of mutations that have negative public health implications.
Variants of concern (VOC)
According to WHO, Variants of Concern cause significant community transmission in multiple countries.
They are known to increase in transmissibility or detrimental change in Covid-19 epidemiology.
They may also cause change in clinical disease presentation or decrease in effectiveness of public health and social measures or available diagnostics, vaccines, therapeutics.
In May 2021, WHO announced using letters of the Greek Alphabet, i.e., Alpha, Beta, Gamma, Delta to name Covid-19 virus variants to ease comprehension.
As of December 2021, five VOCs had been recognized by WHO. They include Alpha, Beta, Gamma, Delta and Omicron.
The Alpha variant is estimated to be 40–80 per cent more transmissible than the wild-type SARS-CoV-2.
It was first detected in November 2020 from a sample taken in September in the United Kingdom, and began to spread quickly by mid-December.
The Beta variant was first detected in South Africa where it emerged with an unusual large number of mutations.
The variant was associated with in-hospital mortality that was 20% higher in the second wave in South Africa than in the first wave.
It was detected in at least 48 states in the US.
The Gamma variant was first identified in Brazil but has spread to more than 10 other countries, including the UK.
Delta variant was first identified in India and its currently the most common type circulating in the UK.
It is regarded as the most contagious form of the SARS-CoV-2 coronavirus so far.
Delta rapidly became the dominant variant of the SARS-CoV-2 virus in the U.S. in 2021.
According to WHO, being fully vaccinated for Covid-19 can protect you from the delta variant, but breakthrough infections sometimes occur.
All three of the authorized Covid-19 vaccines can protect you from the delta variant. For Pfizer and Moderna vaccines, you need both doses for maximum protection.
The Omicron variant was first reported to WHO from South Africa on November 24, 2021.
Image: STAR ILLUSTRATED
It is strikingly different from many other types due to the long list of genetic mutations it has undergone since its recent emergence.
It has now been detected in more than 30 countries and there are signs it may be able to bypass some of our immunity.
But there are also claims that it could be milder than earlier versions of Covid, such as Delta.
According to WHO, "preliminary evidence suggests an increased risk of reinfection with this variant as compared to other VOCs".
Current SARS-CoV-2 PCR diagnostics continue to detect this variant.
Several labs have indicated that for one widely used PCR test, one of the three target genes is not detected (called S gene dropout or S gene target failure) and this test can therefore be used as marker for this variant, pending sequencing confirmation.
Using this approach, this variant has been detected at faster rates than previous surges in infection, suggesting that this variant may have a growth advantage.
"WHO is closely monitoring the spread of the Omicron variant, and studies are ongoing to understand more about these mutations and their impact on transmissibility, virulence, diagnostics, therapeutics and vaccines," the WHO said in its statement on November 30.
It is expected that the Omicron variant will be detected in an increasing number of countries as national authorities step up their surveillance and sequencing activities.WHO
Kenya's Covid-19 positivity rate is at 23 per cent as ongoing community transmission of the Omicron variant has been established.
Twenty-seven sequences (77%) of the 2,169 people who tested positive for the virus on December 18, were confirmed to belong to the Omicron variant.
Two individuals with the Omicron variant had recently travelled from South Africa and Ghana and the rest had no recent international travel history.
Health CS Mutahi Kagwe urged unvaccinated Kenyans to get the jab and those who have been inoculated to observe good hygiene habits including wearing masks and washing hands.
Image: FILE
Variants of interest (VOI)
According to WHO, a variant of Interest has genetic changes that are predicted or known to affect virus characteristics such as transmissibility, disease severity, immune escape, diagnostic or therapeutic escape.
It is also identified to cause significant community transmission or multiple Covid-19 clusters, in multiple countries with increasing relative prevalence alongside increasing number of cases over time, or other apparent epidemiological impacts to suggest an emerging risk to global public health.
WHO has listed two variants under this category, Lambda and Mu.
WHO first identified the Mu Covid-19 variant in January 2021 in Colombia. Since then, scattered cases of the variant have been reported, as well as more significant outbreaks across the world, including other countries in South America, the UK, Europe, the US and Hong Kong.
B September 7,2021, the Public Health England revealed that there were 53 confirmed cases of the Mu Covid variant in the UK.
The Lambda variant was first identified in Peru as early as August 2020.
Initially, Lambda infections were relatively rare. However, in proceeding months Lambda became the dominant variant in Argentina, Chile, and Colombia.
Lambda has been identified in most US States, though the strain has yet to gain traction.
Lambda now accounts for less than one percent of all infections but given its trajectory in Latin America, it is well watching closely.
Vaccine efficacy of emerging variants
Preliminary lab studies show all available Covid vaccines may not be enough defense against the highly contagious Omicron variant.
However, all vaccines still seem to provide a significant degree of protection against serious illness from Omicron, which is the most crucial goal.
But only the Pfizer and Moderna shots, when reinforced by a booster, appear to have success at stopping infections, and these vaccines are unavailable in most of the world.
Although current vaccines may not be a perfect fit for Omicron they are still the best line of defence against Covid.
They have cut the risk of severe illness against the other major Covid-19 variants, including Delta, Alpha, Beta and Gamma.
The WHO has insisted that all National authorities must continue admission of vaccines as a way to fight the virus.
Edited by CM