We’ve seen the Alpha, Kappa and Delta variants cross our borders, but it turns out another strain of the virus that causes COVID-19 has reached our shores.
- The Lambda variant is one of 11 official SARS-CoV-2 variants recognised by the World Health Organization
- It was first detected in Peru and has spread to 29 countries, including Australia
- A new study that has yet to be peer-reviewed found signs that the variant could be more infectious and harder to tackle with vaccination, but it’s early days
The variant, named Lambda by the World Health Organization (WHO) last month, was detected in an overseas traveller who was in hotel quarantine in New South Wales in April, according to national genomics database AusTrakka.
Some reports suggest the new variant could be fast spreading and difficult to tackle with vaccines. So what sets this variant apart from others and should we be concerned?
Here’s what we know so far.
Where did it originate?
Previously known as C.37, Lambda was first detected in Peru in December 2020. Since then, it’s spread to 29 countries, seven of which are in South America.
In April and May this year, Lambda accounted for over 80 per cent of COVID-19 cases in Peru, with a high proportion of cases also in Chile, Argentina, and Ecuador.
On 14 June, Lambda was listed as a ‘variant of interest’ by the World Health Organization due to its vast spread in South America.
Variants of interest are listed as such because they have the potential to be more infectious and severe, but haven’t yet had the devastating impact of those listed as variants of concern.
On 23 June, Public Health England classified it as a ‘variant under investigation’, after six cases were detected in the UK to date, which were all linked to overseas travel.
What makes it different from other variants?
There are now 11 official SARS-CoV-2 variants listed by the WHO.
All SARS-CoV-2 variants are distinguished from one another by mutations in their spike proteins — the components of the virus that allow it to invade human cells.
For instance, the Delta variant first detected in India has two key spike protein mutations — T478K and L452R — that allow it to infect cells more easily and evade the body’s immune response.
According to research published last week but yet to be peer reviewed, Lambda has seven unique spike protein mutations.
A Chilean team of scientists analysed blood samples from health workers in Santiago who had received two doses of the CoronaVac vaccine developed by Sinovac Biotech in China.
They found the Lambda variant has a mutation called L452Q, which is similar to the L452R mutation seen in the Delta and Epsilon variants.
As the L452R mutation is thought to make Delta and Epsilon more infectious and resilient against vaccination, the team concluded that Lambda’s L452Q mutation might also help it spread far and wide.
While it’s possible that Lambda is indeed more infectious than other variants, it’s too early to know for sure, said Kirsty Short, a virologist at the University of Queensland.
“It’s very preliminary,” said Dr Short, who was not involved in the study.
“It’s a good starting point, but I certainly wouldn’t infer anything from that into the clinic.”
Are vaccines still effective against the Lambda variant?
The study also found signs that Lambda’s unique spike mutations could help it slip past the body’s immune response.
The results of the study suggested that the CoronaVac vaccine produces fewer neutralising antibodies — proteins that defend cells against infections — in response to the Lambda variant.
But according to Paul Griffin, who specialises in infectious diseases and vaccines at the University of Queensland, it’s important to remember that these antibodies are just one aspect of immunity.
“We know that [neutralizing antibodies] only tell a part of the story,” said Dr Griffin, who was not involved in the study.
“If that further immunity remains intact, then even with a reduction in neutralizing antibodies, sometimes that protection can still be enough.”
It’s also worth remembering that different vaccines work in different ways to respond to the virus and its variants.
“You can’t really extrapolate from one vaccine,” Dr Short said.
CoronaVac uses inactive versions of SARS-CoV-2 to kick the immune system into gear.
On the other hand, Pfizer contains a single strand of the genetic code that builds the virus’s spike proteins, while AstraZeneca contains a double-strand.
Dr Griffin said that more traditional inactivated vaccines like CoronaVac have proven to be less effective overall than others.
“As a broad category, the inactivated ones have been a little bit underwhelming, particularly compared to others that have such high rates of efficacy,” said Dr Griffin, who was not involved in the study.
While not much is known about how effective the Pfizer and AstraZeneca vaccines are against Lambda, their response to the Delta variant can offer clues.
A recent study from the UK found that two doses of either Pfizer or AstraZeneca are over 90 per cent effective at preventing hospitalisation due to the Delta variant.
Should Australia be worried?
While there has only been one case of Lambda recorded in hotel quarantine in Australia so far, it’s worth keeping an eye on the emergence and spread of SARS-CoV-2 variants around the world, Dr Short said.
“There’s a reason why it’s a variant that we’re watching and looking into more, but it’s certainly not at a point of panic or anything like that.”
Dr Griffin added that Lambda would need to out-compete Delta to become a major concern. “That’s certainly not what we’re seeing,” he said. But as more people get infected, the more chance the virus has to evolve into new variants, Dr Short said.
The best way to tackle this is to focus on getting more people vaccinated, not just in Australia, but globally. “What this should emphasise to everyone is that we need global effort in the vaccination campaign,” Dr Short said.