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Existing vaccines against new variants of COVID-19: Can they hold the fort?


What is this new variant?

A variant is nothing, but a slightly altered or mutated version of a virus. There are thousands of COVID variants present around the world which is to be expected because mutation in viruses is common phenomenon. Most of these mutations are not much of that concern, because they do not provide additional features to the virus.

Omicron is strikingly different from many other types due to the long list of genetic mutations it has undergone, which has increased the infectivity of virus.

What causes a virus to change to a new variant?

When a virus is widely circulating in a population and causing many infections, the likelihood of the virus mutating increases. The more opportunities a virus obtains to spread, the more it replicates – and the more opportunities it gets to undergo changes.

Most viral mutations have little to no impact on the virus’s ability to cause infections and disease. But depending on where the changes are in the virus’s genetic material, they may affect a virus’s properties, such as transmission (for example, it may spread easily) or severity (for example, it may cause severe disease). 

Variants of SARS-COV-2: How do they rise?

Changes to spike

Researchers spotted B.1.1.529 (found in omicron variant) in genome-sequencing data from Botswana. The variant stood out because it contains more than 30 changes to the spike protein — the SARS-CoV-2 protein that recognizes host cells and is the main target of the body’s immune responses. Many of the changes have been found in variants such as Delta and Alpha and are linked to increased infectivity and the ability to evade infection-blocking antibodies.

The apparent sharp rise in cases of the variant in South Africa’s Gauteng province is also raising concerns. Cases increased rapidly in the province in November 2021, particularly in schools and among young people, according to local information. Genome sequencing and other genetic analysis from a team led by Tulio de Oliveira, a bioinformatician at the University of KwaZulu-Natal, found that the B.1.1.529 variant was responsible for all 77 of the virus samples they analysed from Gauteng, collected between 12 and 20 November 2021. Analysis of hundreds more samples are underway.

The variant harbours a spike mutation that allows it to be detected by genotyping tests that deliver results much more rapidly than genome sequencing does. Preliminary evidence from these tests suggest that B.1.1.529 has spread considerably further than Gauteng. It raises concern that this variant may already be circulating quite widely in the country, according to the research team.

Change in spike protein

Vaccine effectiveness

To understand the threat B.1.1.529 poses, researchers will be closely watching its spread in South Africa and other countries. Researchers in South Africa deployed efforts to quickly study the Beta variant, identified there in late 2020, and a similar effort is being organized to study B.1.1.529.

According to Moore’s team — which provided some of the initial data on the ability of Beta variant to dodge immunity — has already begun work on B.1.1.529. They plan to test the virus’s ability to evade infection-blocking antibodies, as well as other immune responses. The variant harbours a high number of mutations in regions of the spike protein that antibodies recognize, potentially dampening their potency. Many mutations we know are problematic, but many more look like they are likely contributing to further evasion - Moore. According to Moore, there are even signals from computer modelling that B.1.1.529 could dodge immunity conferred by another component of the immune system called T cells. Her team hopes to have its first results in short period of time.

An interesting question is ‘does it reduce vaccine effectiveness, because it has so many changes?’,”- asked by Aris Katzourakis, researcher of virus evolution at the University of Oxford, UK. Moore says breakthrough infections have been reported in South Africa among people who have received any of the three kinds of vaccines in use there, from Johnson & Johnson, Pfizer–BioNTech and Oxford–AstraZeneca. Two quarantined travellers in Hong Kong who have tested positive for the variant were vaccinated with the Pfizer jab, according to news reports. One individual had travelled from South Africa; the other was infected during hotel quarantining.

Researchers in South Africa will also study whether B.1.1.529 causes disease that is more severe or milder than that produced by other variants, Lessells said. “The really key question comes around disease severity.”

So far, the threat B.1.1.529 poses beyond South Africa is not clear, researchers indicate. It is also unclear whether the variant is more transmissible than Delta --  Moore, because there are currently low numbers of COVID-19 cases in South Africa. Katzourakis says that countries where Delta is highly prevalent should be tracking for signs of B.1.1.529. “We need to see what this virus does in terms of competitive success and whether it will increase in prevalence.”

How can we prevent future new variants of the COVID-19 virus?

Stopping the spread at the source remains key. Current measures to reduce transmission – including frequent hand washing, wearing a mask, physical distancing, good ventilation and avoiding crowded places or closed settings – continue to work against new variants by reducing the amount of viral transmission and therefore also reducing opportunities for the virus to mutate.

Scaling up vaccine manufacturing and rolling out vaccines as quickly and widely as possible will also be critical ways of protecting people before they are exposed to the virus and the risk of new variants. Priority should be given to vaccinating high-risk groups everywhere to maximize global protection against new variants and minimize the risk of transmission. Moreover, ensuring equitable access to COVID-19 vaccines is more critical than ever to address the evolving pandemic. As more people get vaccinated, we expect virus circulation to decrease, which will then lead to fewer mutations.

Why is it important to get vaccinated even if there are new variants of the virus?

Vaccines are a critical tool in the battle against COVID-19, and there are clear public health and lifesaving benefits to using the tools we already have. We must not put off getting vaccinated because of our concerns about new variants, and we must proceed with vaccination even if the vaccines may be somewhat less effective against some of the COVID-19 virus variants. We need to use the tools we have in hand even while we continue to improve those tools. We are all safe only if everyone around us is safe.

 

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