Issue link: https://maltatoday.uberflip.com/i/1433519
13 maltatoday | WEDNESDAY • 1 DECEMBER 2021 OPINION Jennifer Juno & Adam Wheatley Jennifer Juno is Senior research fellow at The Peter Doherty Institute for Infection and Immunity Adam Wheatley is Senior Research Fellow at the Department of Microbiology and Immunology, The University of Melbourne THE emergence of a new SARS-CoV-2 variant of concern, Omicron, has reig- nited global discussions of vaccine dis- tribution, virus mutation, and immunity against new virus strains. Some experts have suggested the emer- gence of a new strain could be a result of low levels of vaccine coverage in develop- ing 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. Viruses naturally change during repro- duction A virus is life at its most simple, and essentially contains two main elements: (1) a blueprint for reproduction (made of DNA or RNA), and (2) proteins that let the virus enter cells, take over, and start replicating. While only a few SARS-CoV-2 viruses are needed to cause an infection, replica- tion 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. Importantly, the process of duplicating the virus' RNA is imperfect. Eventual- ly, errors will accumulate in the growing pool of viruses, causing what we refer to as virus variants. What is a SARS-CoV-2 variant virus and why are some of them concerning? When viruses are transmitted from one person to another, some of the new vari- ants will be better at entering cells or du- plicating themselves than others. In these cases, the "fitter" variants are more likely to take over and become the main virus that replicates within a popu- lation. Over the course of the pandemic, this has occurred 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 Al- pha variant and now, the Delta variant. 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. How are vaccines holding up as the virus changes? Our current vaccines are still highly ef- fective against SARS-CoV-2 variants, in- cluding the Delta strain. This is because the vaccines target the whole "spike" pro- tein of the virus, which is a large protein with a relatively small number of changes across variants. Concerningly, some SARS-CoV-2 var- iants (Beta, Gamma, Lambda and Mu) have been reported to "evade" immunity from vaccination. This means the im- mune system is unable to recognise the variant virus as well as the original strain, which reduces the effectiveness of vacci- nation. However to date, the global impact of such "immune escape" strains has been limited. For instance, the Beta variant, which showed the highest amount of im- mune escape, was unable to out-compete Delta in the real world. Are low vaccination rates a risk for generating new virus variants? For now, any relationship between vac- cine coverage and new SARS-CoV-2 var- iants is unclear. There are two main factors that could lead to the development of new variants. First, low vaccine coverage might in- crease 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 mu- tate. Alternatively, as vaccination rates rise, the only viruses that will be able to suc- cessfully infect people will be variants that at least partially escape the protec- tion of vaccines. This scenario might require continual global surveillance efforts and new vac- cines to maintain long-term control of the virus, similar to the flu. Either way, with COVID-19 almost cer- tain 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. So where did Omicron come from? The recent reports of a new variant of concern, Omicron, has raised global alarm bells. Discovered by the impressive virus se- quencing efforts of South African scien- tists, Omicron contains an incredible 32 changes in the spike protein alone. This includes mutations that can increase transmission and evade immunity. So there is a risk that Omicron may spread rapidly and reduce (but not elim- inate) the effectiveness of current vac- cines. With low overall vaccination coverage in southern Africa (albeit with higher pop- ulation level immunity from infection), some have suggested global inequities in the supply of COVID vaccines may be re- sponsible for the emergence of Omicron. However, the extensive mutations in Omicron are also consistent with the vi- rus changing over an extended time, as it replicated in a person with a compro- mised immune system. Such highly mutated variants have been documented in the past but have general- ly not spread widely. Global vaccine coverage benefits us all 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 immuno- compromised 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 high- ly interconnected, countries will struggle to keep their citizens safe in the face of pandemic threats without embracing a framework for greater international co- operation and coordination. theconversation.com Are new COVID variants like Omicron linked to low vaccine coverage? High vaccine coverage lessens the chance a highly mutated virus can spread