The subvariants and mutations of COVID-19, explained

COVID-19 was first detected in late 2019, but in the more than four years since, the disease has been through several different mutations.

While infecting hundreds of millions of people worldwide, the disease has changed and evolved.

Along the way it became more dangerous in some instances, and milder in other cases.

But whenever one mutation became the dominant variant, it was because it was more infectious than others, and more effective at subverting antibodies.

A new COVID-19 variant called XEC was first detected in Australia in October 20204.

Monash University epidemiology and preventive medicine Associate Professor James Trauer said two variants have combined to create XEC, an Omicron subvariant, which may become the new dominant type.

XEC is a combination of FLiRT and FLuQE, according to COVID-19 data analyst Mike Honey.

Experts say it responds to current vaccines.

Click through to see the other variants and subvariants that have appeared – and disappeared – during the pandemic.

Wild COVID-19 is the initial or ancestral strain of the virus, as it emerged in Wuhan in 2019.

It appeared to have formed from a cross-species transmission between two different coronaviruses linked to bats and pangolins.

The term "wild-type" infers the virus developed outside of any human influence, though some suggest the disease may have leaked out of a laboratory in the Chinese city.

It was replaced as the dominant virus with the spread of Alpha.

Alpha was first detected in October 2020 in the UK, and was blamed on a substantial spike of COVID-19 in the country.

It was considered to be 40 to 80 per cent more transmissible than wild COVID-19.

However, while more infectious, there was little indication Alpha was any more deadly than the original virus.

It is no longer a variant of concern.

Beta was detected in December 2020 in South Africa.

The Beta variant was found to be more prevalent among young people with no underlying health conditions.

It is no longer circulating.

Gamma was first detected in January 2021 and traced back to Brazil.

The virus produced nearly 10 times more viral load than previous variants and was more than twice as transmissible as previous variants.

It was found Gamma was 10 to 80 per cent more lethal.

It is no longer a variant of concern.

Delta was the deadliest of the variants, and the one that forced much of Australia into lockdown in 2021.

The variant was first discovered in India in October 2020 and rapidly went around the world, becoming by far the dominant variant.

Deadlier than previous variants, it is one of the most contagious respiratory diseases on Earth.

But the devastating impact of Delta was blunted by the vaccines, which were effective in stopping the transmission of nearly all cases.

Kappa is a sub-variant of Delta, and was first detected in India in December 2020.

Kappa spread in Melbourne in June last year but was susceptible to the vaccine and is no longer considered a circulating variant of concern.

Lambda and Mu were two variants detected in South America in late 2020 and early 2021.

Both cases spread to dozens of countries around the world.

But with the efficacy of vaccines and the dominant spread of Delta, both Lambda and Mu were downgraded to "previously circulating variants of concern".

Omicron rapidly became the dominant strain after it was first detected in Botswana in November 2021.

The disease was considered milder than previous variants but much more infectious.

Omicron was able to elude antibodies of the double-vaccinated, forcing the reliance on booster shots.

While the virus remains dangerous and deadly, the vaccine is effective at reducing the impact of Omicron. 

Unlike other variants, the loss of smell and taste is a less common symptom of Omicron.

BA.2 is a subvariant of Omicron, first detected in November 2021.

By January 2022, it had spread to every continent. It is considered 30 to 60 per cent more transmissible from the original Omicron, identified as BA.1.

The subvariants BA.4 and BA.5 became the dominant strains circulating in Australia during the wave of infections in July/August of 2022. The strains were more infectious than previous subvariants and more effective at eluding the impact of vaccines.

The subvariants also elude antibodies caused by previous illnesses, meaning people can develop COVID-19 from BA.5 weeks after last developing the illness.

A range of Omicron subvariants were circulating in early to mid-2023, with XBB 1.16 – colloquially known as "Arcturus" – designated as a variant of interest by the World Health Organisation (WHO).

Originally detected in NSW in January, on April 17 the WHO said XBB 1.16's increasing prevalence, as well as its increasing growth advantage, made it a variant of interest.

The WHO said the subvariant reached 32 nations beyond Australia, and that the vast majority of cases have been recorded in India.

While Arcturus was reported as being able to evade immune responses better than some other variants and subvariants, the WHO said it didn't pose a significant additional health risk.

"While growth advantage and immune escape properties are observed in different countries and immune backgrounds, including in countries where XBB.1.5 has become the dominant variant recently, no changes in severity have been reported in countries where XBB.1.16 are reported to be circulating," the WHO said in its initial risk assessment.

"In India and Indonesia, there has been a slight increase in bed occupancy numbers. However, the levels are much lower than seen in previous variant waves."

XBB 1.16 is closely related to another Omicron subvariant, XBB 1.5.

Named after the Greek goddess of strife and mischief, the Eris subvariant of COVID-19 became the dominant strain of the virus in the US and UK by August 2023.

Technically known as EG5.1, it's yet another Omicron subvariant.

It was first detected in Australia in April 2024, with fewer than 100 cases of the strain recorded over the space of about four months.

Experts said it was unlikely to be any more virulent or deadly than any of its predecessors, although it is highly contagious.

JN.1, a sublineage of BA.2.86, was first detected in August 2023.

Its presence rapidly increased globally and had experts expecting the strain to become the most dominant variant in 2024.

The new strain led to a surge of infections in Victoria and sparked the highest number of hospitalisations in the state in six months.

Not a single variant, FLiRT refers to a family of subvariants that all mutated from JN.1, with shared specific mutations to their spike proteins.

The strains include KP.2, KP.3, JN.1.7 and a whole range of others which typically start with either "JN" or "KP".

KP.2 is of particular note here. It first emerged in January 2024 and became the dominant strain in the United States in May.

It also spread to other countries, including Australia.

The LB.1 covid strain was also similar.