Infectious diseases experts say the Victorian government should not be using alarming language to describe the Kappa variant – responsible for the state’s current Covid outbreak – after officials claimed it was spreading “faster” and through “fleeting” or “low contact” between strangers.
The acting Victorian premier, James Merlino, said on Tuesday “at least one in 10 current cases have caught this virus from a stranger”. He said the virus was being spread through “people brushing against each other in a small shop, getting a take-away coffee from the same cafe, being in the same place, at the same time, for mere moments”.
The Victorian Covid commander, Jeroen Weimar, said: “People unknown to each other before have transmitted to each other. That is very different from what we have seen before. It is certainly the fastest-moving outbreak we’ve seen anywhere in Australia for a long time.”
‘No different’ to previous outbreaks
But an infectious diseases physician at St Vincent’s hospital in Sydney, Prof Greg Dore, who is running a study looking at long-haul Covid patients, said the Kappa variant was acting “the same as we’ve seen before” with other variants in Australia.
“There just isn’t any strong evidence this variant is more efficiently transmitted than previous variants,” said Dore, who is also a clinical researcher with the Kirby Institute.
“There have been examples in previous outbreaks where a very short duration of exposure has then led to infections, such as the Berala BWS cluster in New South Wales, where people going to a bottle shop for a short period of time were becoming infected through what was almost certainly aerosol transmission. There’s nothing different in terms of how this virus is being transmitted in Melbourne right now.”
The variant involved in Melbourne’s outbreak was first identified in India and has recently been renamed from the B.1.617.1 variant to the Kappa variant by the World Health Organization, which also describes it as a “variant of global interest”.
Coronavirus variants now being named after letters of the Greek alphabet instead of their place of first discovery, in a move to avoid stigma.
Kappa and the related but more infectious Delta variant, described by WHO as a “variant of global concern”, are responsible for surges of Covid in India. Delta has now overtaken Kappa as the dominant variant in India and also the UK.
There is an important difference between the WHO definitions of “variant of concern” and “variant of interest”. The former have increased transmissibility, virulence or change in clinical disease, and a decreased effectiveness of public health and social measures.
Variants of interest, such as Kappa, are those shown to cause community transmission in multiple clusters, and which have been detected in multiple countries, but have not yet necessarily proven to be more virulent or transmissible.
Both Delta and Kappa may slightly reduce the efficacy of some vaccines, the head of the biosecurity research program at the Kirby Institute, Prof Raina Macintyre, said.
“There is also anecdotal evidence coming from India that Kappa might have a slightly different clinical presentation to the Delta strain and the other variants, so abdominal pain, diarrhoea and gastrointestinal symptoms rather than the more typical respiratory symptoms,” she said.
“So I think an important message is you need to be on high alert for any of these symptoms and to present for testing.”
However, there is not enough evidence yet for WHO to have upgraded Kappa’s category to a variant of concern.
Infectiousness involves more than the variant
But even if Kappa is more infectious in India, this could be to do with a variety of factors beyond just the biology of the variant. Sanjaya Senanayake, an infectious diseases expert and associate professor of medicine at the Australian National University, said public health measures such as social distancing and lockdowns also impacted spread.
There was not enough data on Kappa in Victoria – where there are 60 active cases – to definitely say it was spreading differently, Senanayake said on Wednesday.
“In Australia, we haven’t had the issues with variants that other countries have,” he said.
In February, Queensland locked down for three days after the Alpha variant, first identified in the UK and which spread rapidly there, entered the Brisbane community from hotel quarantine. It was quickly contained.
The Alpha strain is said to be 50-60% more infectious than the D614G strain identified in China, which was the first variant and became the dominant strain globally by June 2020, Senanayake said.
“But in Australia, we haven’t had that issue seen in the UK in terms of big outbreaks of Alpha,” he said. “There are multiple reasons why a variant might behave differently, and yes, part of that may be biological but not everything can be subscribed to a strain being biologically different.”
Population density and public health measures also played a role, he said.
“Poor testing, poor messaging, all those sorts of things play a role in pace of spread in other parts of the world, as well as ventilation.
“So it could be an environmental issue, not just a biological. It’s worth Victoria raising issues of concern about fleeting contact, but in a few days it might be through further investigations we discover there was in fact closer contact involved. It is important to be really careful with the messaging and not say yet that it is definitely spreading differently. We can’t know that’s the case with any certainty yet.”
So why are Victorian government officials saying it repeatedly?
Dore said part of the reason Victorian government officials were emphasising the so-called fleeting spread was “they want to make sure people are not complacent about coming forward for testing”.
“They are trying to push the appropriate message that anyone who has been to exposure sites or who have symptoms should get tested and be vigilant,” he said. “But you can already see community response in terms of testing has been absolutely amazing, which tells you that the community is already on side. So I think the government needs to pull that language back a bit.”
An infectious diseases professor at the Australian National University, Peter Collignon, said with a lockdown in place – which on Wednesday was extended for another week – the government needed to ensure the public followed the rules. Emphasising the infectiousness of the virus could help with that, he said.
“There are severe restrictions in place, and then there’s this whole argument about New South Wales doing it differently to Victoria, without shutting borders and locking down, but with the same end result,” Collignon said.
Dore believes NSW had “taken the right stance” in not closing the border, even as it was revealed that one Victorian Covid case travelled through NSW while potentially infectious.
“It shows the public that NSW has confidence in its public health systems and their ability to test and contain without resorting to harsh measures – and that demonstration of public confidence is really crucial,” Dore said. “It would be good if other jurisdictions weren’t so trigger-happy in terms of border closures.”
Nonetheless, concern is warranted
There is nonetheless “real concern” among health authorities that the Kappa variant may spread beyond Victoria, according to the director of Australia’s Immunisation Coalition, Prof Robert Booy, because the immunisation of vulnerable populations is not yet complete. Booy said national cabinet must urgently consider ways to vaccinate vulnerable Australians yet to receive their first dose.
If data did go on to show that Kappa had mutated to infect and transmit more easily, vaccination would be key to preventing severe disease and death, he said.
“The rest of Australia is concerned, including epidemiologists and infectious disease experts, who recognise that the threat from this Indian variant may well be increased,” Booy said.
“We should optimise measures of control and we need to get, especially, our at-risk populations and those who care for them vaccinated as soon as possible, Australia-wide, not just in Victoria.”