Australia has noticed SARS-CoV-2 (the virus that causes COVID-19) escape on numerous occasions from hotel quarantines, including in Melbourne, Perth, and Brisbane. These events have been particularly worrying because they involved people infected with “variants” of the virus.
But what especially are these variants, and how concerned should we be?
What’s a variant?
Viruses can’t expand and replicate on their own. They require a host, and they need to capture the cells of the host to replicate. When they replicate in a host, they face the difficulty of replicating their genetic material. For several viruses, this isn’t a specific process, and their offspring often contain errors — meaning they’re not precise copies of the original virus.
These errors are known as mutations, and variants are viruses with these mutations. Often, these mutations don’t change the biological traits of the virus. That is, they don’t have any influence on how the virus causes disease or replicates.
Some mutations can weaken the virus’s ability to transmit or replicate. Variants with such mutations are swiftly dropped from the viral population.
Hardly, though, variants arise with an advantageous mutation, one that means it’s better at spreading, replicating, and avoiding our immune system. These variants have a particular advantage (in biological terms, they are “fitter” than other variants) and may quickly become the dominant viral strain.
There’s some concern we’re noticing an increasing number of variants with advantageous mutations, adding to the rigor of the COVID-19 pandemic.
Here’s a look at the main three variants you might’ve heard about in the media.
The ‘UK variant’ — B.1.1.7
This variant emerged in the fall of 2020 in the United Kingdom. It has a large number of mutations, many of which involve the virus’ spike protein, which helps the virus penetrate human cells.
It has transmitted quickly throughout the UK since it emerged, and to at least 70 other countries, including Italy and Australia.
The fact it has spread so quickly and rapidly replaced other circulating variants hints it has some kind of particular benefit over other variants.
After analyzing the data surrounding the new variant, the UK New and Emerging Respiratory Virus Threats Advisory Group (NERVTAG) concluded it “had modest confidence” the variant is considerably more contagious than other variants.
This may be the outcome of one of the mutations in the spike protein of the variant — a mutation called “N501Y”. One preprint document, uploaded last month and yet to be peer-reviewed, found N501Y linked with enhanced binding of the virus to a receptor observed on the surface on many of our cells, called “ACE2”. This could indicate the variant is even more effective at penetrating our cells.
Although initially, the variant wasn’t showing severe COVID symptoms, current data have guided NERVTAG to conclude there’s “a genuine possibility” that infection with the variant “is linked with an increased risk of death” corresponded with non B.1.1.7 viruses.
However, the organization accepted there are certain limitations, and this remains an evolving condition.
The ‘South African variant’ — B.1.351
This variant was first reported in Nelson Mandela Bay, South Africa, in samples dating back to the beginning of October 2020. Since then it has been detected in more than 30 countries including the United States.
Similar to the UK variant, it also has the N501Y mutation in the spike protein, meaning it’s more effective at penetrating our cells to replicate. This may help to explain its speedy transmission.
It also consists of several other concerning mutations. Two of these, called “K417N” and “E484K”, are bad news for our immune system. They can lessen how well our antibodies bind to the virus (however, this is also based on preprint data expecting peer evaluation).
But there’s no data yet to propose the South African variant is more deadly than the original variants.
The Brazilian P.1
The P.1 variant was first detected by the National Institute of Infectious Diseases (NIID) in Japan in four travelers from Brazil in January 2021, sampled during routine screening at Haneda airport outside Tokyo.
It’s now common in the Brazilian state of Amazonas and has been reported in countries including the United States and South Korea.
Similar to the South African variant, the Brazilian variant has the spike protein mutations K417N, N501Y, and E484K (as well as several other mutations).
While there’s no confirmation this variant causes more critical disease, there’s concern it has facilitated a wave of reinfections in Manaus, the biggest city in Amazonas, which was estimated to have reached “herd immunity” in October last year.
What does this mean for vaccines?
Major vaccine developers are examining the effectiveness of their vaccines against different variants. Usually, the currently licensed vaccines defend comparatively well against the UK variant.
But recent phase 2/3 data from both Johnson & Johnson and Novavax suggest decreased protection against the South African variant. The Oxford/AstraZeneca vaccine group also released data proposing its vaccine gives only minimal protection against mild-moderate disease originated from this variant.
However, it’s essential to know reduced protection doesn’t mean any protection at all, and that data is still emerging.
What’s more, various vaccine companies are now studying whether tweaks to the vaccines can enhance their performance against the different variants.
The take-home advice is that variants will appear, and we need to strictly control their spread. Though, there’s every sign we’ll be able to adapt our vaccine policies to protect against these and future variants.
Originally published on The Conversation.