The emergence of a new SARS-CoV-2 variant of concern, Omicron, has reignited global discussions of vaccine distribution, virus mutation, and immunity against new virus strains.

Some experts have suggested the emergence of a new strain could be a result of low levels of vaccine coverage in developing nations.

So how do new virus variants emerge? And what role does vaccination play? The relationship is still unclear but here’s what we know so far.

While only a few SARS-CoV-2 viruses are needed to cause an infection, replication of the virus in the lungs is explosive.

Millions of virus particles are eventually produced, and some of these viruses are then exhaled to infect another host.

When viruses are transmitted from one person to another, some of the new variants will be better at entering cells or duplicating themselves than others.

In these cases, the “fitter” variants are more likely to take over and become the main virus that replicates within a population.

Every time someone gets infected with SARS-CoV-2, there is a chance the virus could generate a more fit variant, which could then spread to others.

Our current vaccines are still highly effective against SARS-CoV-2 variants, including the Delta strain.

This is because the vaccines target the whole “spike” protein of the virus, which is a large protein with a relatively small number of changes across variants.

Concerningly, some SARS-CoV-2 variants (Beta, Gamma, Lambda and Mu) have been reported to “evade” immunity from vaccination.

This means the immune system is unable to recognise the variant virus as well as the original strain, which reduces the effectiveness of vaccination.

For now, any relationship between vaccine coverage and new SARS-CoV-2 variants is unclear.

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

First, low vaccine coverage might increase the risk of new variants by allowing transmission within a community.

In this case, high viral replication and person-to-person transmission provides plenty of opportunity for the virus to mutate.

This scenario might require continual global surveillance efforts and new vaccines to maintain long-term control of the virus, similar to the flu.

Either way, with COVID-19 almost certain to stick around, we should expect new strains will continue to be a challenge. We will need careful and active management to address this risk.

The recent reports of a new variant of concern, Omicron, has raised global alarm bells.

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

With low overall vaccination coverage in southern Africa (albeit with higher population level immunity from infection), some have suggested global inequities in the supply of COVID vaccines may be responsible for the emergence of Omicron.

Such highly mutated variants have been documented in the past but have generally not spread widely.

Expanding global vaccine coverage by increasing supplies, ensuring equitable distribution, and combating hesitancy and misinformation remains critical.

High global vaccine coverage will limit overall viral evolution, protect immunocompromised people and lessen chances highly mutated viruses can spread, all of which can directly or indirectly lower the risks of new variants emerging.

With the global community now 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 with the Peter Doherty Institute of Infection and Immunity and Adam Wheatley is with the University of Melbourne)

(This is an opinion piece and the views expressed above are the author’s own. FIT neither endorses, nor is responsible for them. This article was originally published on The Conversation. Read the original article here.)