“Globally the conditions are ideal for more variants to emerge. To change the course of the pandemic, we must change the conditions that are driving it.”

– Tedros Adhanom Ghebreyesus, WHO Director-General

INTRODUCTION

At the time of this writing, Canada (and, indeed, most of the world) is still in the midst of the Omicron wave of the COVID-19 pandemic. The Omicron variant of SARS-CoV-2 (the virus that causes COVID-19) is remarkably transmissible, with experts predicting that one person can infect between three to five additional people on average (Scribner, 2021). 

It’s the latest in a growing list of SARS-CoV-2 variants that have emerged as the virus has mutated over time. Mutations are a common phenomenon among most viruses, and most are relatively harmless. But some can produce more transmissible and/or severe variants capable of dealing significant damage to healthcare and public health systems. As more SARS-CoV-2 variants continue to emerge, many are left wondering about the implications for current vaccines and how the trajectory of the pandemic may be affected. 

In this blog post, we’ll be discussing:

• Viral mutations and COVID-19: a brief timeline
• Variants and vaccines
• Long-term implications: the future of life with COVID-19

Viral mutations and COVID-19: a brief timeline

A mutation, put simply, is a change in the genomic sequence of an organism or virus. Mutations can occur for a number of different reasons, including DNA copying errors, exposure to ionizing radiation, or exposure to chemical mutagens (National Human Genome Research Institute, n.d.). 

In the case of COVID-19, mutations occur when the virus makes a copying error during replication (World Health Organization, 2021). This causes the virus’s genetic material to change slightly, which in some cases results in a viral strain that is more transmissible and/or severe than its ancestor. Mutations of this type are most likely to occur if the virus is circulating widely and causing many infections, thus giving it more opportunities to undergo changes as it replicates (World Health Organization, 2021). 

Several SARS-CoV-2 mutations with varying levels of severity have been identified by scientists around the world since early 2020. To track these mutations, the WHO uses a classification system to characterize the significance of new variants as they appear. These classifications are:

• Variant Under Monitoring (VUM): a variant with genetic changes that may affect virus characteristics, but epidemiological and phenotypic evidence is insufficient to determine exact severity
• Variant of Interest (VOI): a variant that possesses genetic changes that are predicted or known to affect various virus characteristics and has caused significant community transmission or multiple COVID-19 clusters
• Variant of Concern (VOC): a variant shown to be more transmissible, more severe, and/or more capable of evading existing public health measures and treatment options (World Health Organization, 2022)

A variant may be reclassified (e.g. changed from a VOI to a VOC) as more information about its properties becomes known. To date, the WHO has identified five SARS-CoV-2 variants as VOCs, the highest variant classification. See below for a timeline of their emergence:

Variants and vaccines

What do all these variants mean for vaccine effectiveness and population immunity?

Unfortunately, more variants means greater potential for immune escape among those who have been vaccinated or recovered from a COVID-19 infection. This is because existing COVID-19 antibodies (which were generated based on previous strains of the virus) are less effective at recognizing the mutated virus, thus making them less effective at preventing infection (Doctrow, 2021).

The good news is that current vaccines are still proving significantly effective against severe illness, hospitalization, and death from COVID-19. A UK study found that those with 2 doses of a COVID-19 vaccine who became infected were about 65% less likely to be admitted to hospital with an Omicron infection than those who were unvaccinated (UK Health Security Agency, 2021). Booster shots reduce this risk even further, with studies finding them to be about 90% effective at preventing hospitalizations (Thompson et al., 2022), and 61% effective at preventing symptomatic infection altogether (Buchan et al., 2022). 

What’s more, vaccine manufacturers are also working on variant-specific versions of the COVID-19 vaccine. In early December 2021, Pfizer and BioNTech announced that they were developing a vaccine specific to the Omicron variant that would provide even more robust protection against both infection and severity than their original product (Pfizer, 2021). Assuming the vaccines are successful, this technology could significantly impact our ability to manage any future variants. 

Long-term implications: the future of life with COVID-19

We’ve got vaccines. We’ve got variant-specific boosters. What does this all mean for the future of COVID-19?

Frequent and regular variants likely mean that COVID-19 will be with us for the foreseeable future. Vaccines, however, will hopefully continue to provide significant protection against severe disease and death, rendering SARS-CoV-2 much less of a threat to public health and health systems capacity for countries that have access to them. Booster doses and variant-specific vaccinations should also significantly reduce transmission of the virus and decrease the risk of further variants emerging. 

Many experts believe that this will eventually lead COVID-19 to transition into an endemic or seasonal epidemic disease. In contrast to a pandemic disease, which grows exponentially across multiple countries, an endemic disease is one that circulates regularly in certain regions (Columbia, 2021). An epidemic disease causes a large increase in cases across a particular region or country (Columbia, 2021) and may occur seasonally (as is the case with influenza) (Centers for Disease Control and Prevention, 2018). These phases of disease transmission are generally much more predictable and easier to control than pandemics, meaning strict emergency measures like lockdowns are generally not needed to mitigate their impact on the healthcare system. 

There will, however, still be many challenges to overcome. While diseases circulating at endemic/epidemic levels are easier to manage, healthcare systems may still be at risk of becoming overwhelmed. Scholars Telenti et al. (2021) note that even if vaccinations and effective antiviral treatments are able to render the burden of SARS-CoV-2 infection levels equal to that posed by influenza, it would still cause between 250 000 and 500 000 annual deaths worldwide. This would put considerable long-term strain on healthcare services, requiring significant adaptations and capacity expansions.

Furthermore, the full benefits of a post-pandemic world will only be achieved if everyone is equally able to access the available technologies and treatments to prevent COVID-19. According to Our World in Data, 61.6% of the total global population has received at least one dose of a COVID-19 vaccine (Our World in Data, 2022). But in low-income countries, that figure drops to just 10.6% (Our World in Data, 2022). This means that billions are still at risk of developing severe outcomes from a COVID-19 infection. Moreover, undervaccination also increases disease transmission, which in turn increases the risk of even more new variants emerging and wrecking global havoc. Governments must therefore take these challenges into account as they develop new policies to adapt to life with COVID-19 and its variants. 

Conclusion

COVID-19 variants have undoubtedly set us back a few steps in our mission to end the global pandemic. But vaccines and public health measures can bring us closer to a more sustainable future with COVID-19 – if they are distributed and used effectively. In this blog post, we’ve discussed:

• the definition of a virus mutation and current COVID-19 VOCs;
• the impact of variants on vaccine effectiveness and the development of variant-specific COVID-19 vaccines;
• the long-term reality of life with COVID-19 and the transition from the pandemic phase to the endemic/epidemic phase

Written by: Claire Borgaonkar, BPAPM (c)