Are new Covid-19 mutants like Omicron associated with low vaccination rates?

“Conversation” by Jennifer Junho and Adam Wheatley

The emergence of a new SARS-CoV-2 variant of concern, Omicron, has rekindled global debate about vaccine distribution, viral mutations, and immunity to new viral strains.

Some experts suggest that the emergence of new strains may be the result of low vaccination rates in developing countries.

So how do new virus variants emerge? And what role does vaccination play? The relationship is still unknown, but what we know so far is:

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Viruses change naturally during reproduction Viruses are the simplest life and contain essentially two major components: (1) reproductive blueprint (made of DNA or RNA), and. (2) Proteins that invade cells and take over the virus, and start replication.

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Very few SARS-CoV-2 viruses are needed to cause infection, but viral replication in the lungs is explosive. Eventually, millions of virus particles are produced, some of which are exhaled and infect another host.

Importantly, the process of replicating viral RNA is incomplete. Eventually, an ever-growing pool of viruses accumulates errors, resulting in what are called virus variants.

What is the SARS-CoV-2 variant virus? Why are some of them concerned?

When the virus is transmitted from person to person, some of the new variants are better at invading cells and replicating themselves than others.

In these cases, the “fitter” variant is more likely to take over and become the major virus that replicates within the population.

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During the pandemic process, this happened several times. The original SARS-CoV-2 virus that emerged from Wuhan in 2019 was later replaced by a variant called D614G, followed by the Alpha variant, and now the Delta variant.

Every time someone gets infected with SARS-CoV-2, the virus produces a more appropriate variant, which can spread to others.

How does the vaccine withstand changes in the virus?

Our current vaccine is still very effective against SARS-CoV-2 mutants, including the Delta strain. This is because the vaccine targets the entire “spike” protein of the virus. This is a large protein with relatively little change between mutants.

Of concern, some SARS-CoV-2 variants (beta, gamma, lambda, mu) have been reported to “avoid” immunity from vaccination. This means that the immune system cannot recognize the mutant virus as it did in the original strain, reducing the effectiveness of vaccination.

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However, to date, the global impact of such “antigenic” strains is limited. For example, the beta variant that showed the most antigenic escape could not beat Delta in the real world.

Is there a risk of new viral variants being produced if the vaccination rate is low?

At present, the relationship between vaccine coverage and the new SARS-CoV-2 mutant is unknown.

There are two main factors that can lead to the development of new variants.

First, the narrow coverage of the vaccine may increase the risk of new variants because it allows infection within the community.

In this case, high viral replication and human-to-human transmission provide ample opportunity for the virus to mutate.

Alternatively, as vaccination rates increase, the only virus that can successfully infect people will be mutants that at least partially escape vaccine protection.

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This scenario, like influenza, may require continuous global surveillance efforts and new vaccines to maintain long-term control of the virus.

In any case, Covid-19 is almost certainly established, so we should expect new strains to continue to be challenged. Dealing with this risk requires careful and proactive management.

So where did Omicron come from?

Recent reports of a new mutant of concern, Omicron, have sounded a global alarm.

Discovered by an impressive virus sequencing effort by South African scientists, Omicron contains 32 amazing changes in peaplomer alone. This includes mutations that can increase transmission and evade immunity.

Therefore, there is a risk that Omicron will spread rapidly and may reduce (but not eliminate) the effectiveness of current vaccines.

Due to low overall vaccination rates in South Africa (although population-level immunity to infection is high), some suggest that global inequality in the supply of Covid vaccines may be responsible for the emergence of Omicron. increase.

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However, widespread mutations in Omicron are consistent with long-term changes in the virus, as they are replicated in people with a weakened immune system.

Such highly mutated variants have been documented in the past, but are generally not widespread.

Global vaccine coverage benefits all of us It is still important to increase supply, ensure equitable distribution, and expand global vaccine coverage by fighting hesitation and misinformation. is.

High global vaccination rates limit the evolution of the virus overall, protect people with immunodeficiencies, and reduce the chances of the spread of highly mutated viruses. All of these can directly or indirectly reduce the risk of new variants emerging.

With the global community highly interconnected, countries will struggle to keep their citizens safe in the face of pandemic threats without embracing a framework for greater international cooperation and coordination.

(Jennifer Juno is a Senior Research Fellow at the Peter Doherty Institute for Infectious Immunology and Adam Wheatley is a Senior Research Fellow at the Faculty of Microbial Immunology, University of Melbourne)

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