EXPERT REACTION: What do we know about Victoria's COVID-19 variant?

Most scientists who understand respiratory aerosols realised COVID-19 was airborne by mid-2020. The virus can linger in the air for 3-16 hours, shown in several research studies. This means transmission risk is greatest indoors, especially in poorly ventilated settings. Many studies show that most transmission occurs indoors.

Fleeting contact may result in infection if the air is laden with infected aerosols, from an infected person having been there for a while simply breathing, or even briefly if they sneezed or coughed. The B1617 [Kappa and Delta] variants appear to result in higher viral loads, so therefore may result in more airborne virus.
 
In Brighton, it would be important to know if the infected person and contact visited the toilets. That is more likely to be the source of infection than outdoor dining.

The virus is excreted in the faeces, and flushing generates massive aerosolisation, so you could breathe in faecal aerosols in the toilet. A few studies on aircraft (which have very high ventilation rates) identified the toilet as the main risk factor, in one case where someone took off their mask in the toilet.
 
We do not have a precise quantitation of transmissibility for Kappa, as it is far less well studied than Delta, but it has mutations that may make it more transmissible, and the communications from the Victorian CHO suggest their data are very worrying.

The closely related Delta variant is 50 per cent more transmissible than the Alpha variant, which was already 50-100 per cent more transmissible than the main 2020 strain. So for Delta, the R0 may be as high as 7 (based on being 50 per cent more transmissible than Alpha) as estimated by Public Health England.

Delta is dominant in the UK, and there has not been as much gene sequencing in India, so we know less about Kappa, but based on the mutations it possesses and the reports from Victoria, it is likely at least as transmissible as Alpha or more. Kappa also has the 484Q mutation which will make it more vaccine-resistant than Delta (which in itself has been shown to have some vaccine escape).

I think we have to be careful and measured with our use of language when it comes to the situation in Victoria. It's certainly true that we are facing a different variant in this cluster that has been reported to be more infectious than other strains. However, we are still facing the same virus and it still behaves in a similar way in all other respects to the original strain that emerged in 2020. So whilst the increased infectiousness presents an additional challenge which means we have to work even harder to limit transmission, it's important to put any fear and anxiety into perspective.

We also need to understand that a lot of what we are seeing and are aware of now in terms of the links between cases may be as a result of the improved contact tracing that is being done in Victoria and the more thorough understanding we have of how the virus has moved from one person to the next. I think this explanation is more likely than one in which the virus has changed dramatically in its characteristics.

Although what we have faced during the pandemic has altered all of our perspectives and we’ve seen how quickly the evidence can change, and we need to be prepared to respond to changed information, I would like to see more robust data before I am fully convinced that this variant of the virus is behaving in a very different way to what we have already seen.

There is insufficient evidence to date to support the proposition that the Kappa variant is especially more easily transmitted. Transmission really depends on how much virus there is in the environment, which is dependent on the level of viral shedding occurring at the crucial time and the level of air circulation and/or clearance, as well as the susceptibility of others in the space affected.

In the right circumstances, transmission has been known to occur very quickly and easily – sometimes even before symptoms have appeared in the infected individual. Because of these ‘perfect storm’ events, people have often speculated about the possible existence of a new ‘super spreading’ strain of COVID-19.

In reality, firm evidence of increased transmissibility has only really been associated with a few variants, such as the Alpha variant which was found to be moderately more transmissible, perhaps up to 70 per cent. It may well turn out that the Kappa variant is more transmissible, but the jury is not yet in as it does take time to review the evidence.

Delta strain (B.1.617.2) is labelled by the WHO as a Variant of Concern (VOC), while the Kappa Strain (B.1.617.1) is labelled as a Variant of Interest (VOI). Both originated in India late last year, but the Kappa strain is thought to be less infectious and virulent than the Delta strain.

The WHO is more worried about VOCs, as they are more transmissible, virulent, and difficult to control with existing public health measures.  

The current Melbourne outbreak is due to the Kappa strain. According to the Victorian Health Department, around 10 per cent of cases “caught this virus in those casual contact settings outside the workplace or the family home” and “some cases have come from fleeting contact between Victorians”. 

I think there is no reason to reject this observation. Currently, there are limited studies on the transmissibility of various COVID-19 variants and most data is observational. Although the Kappa strain is reported to be less infectious in other countries, this could be due to inadequate surveillance (e.g. in the case of India) or high vaccine coverage (e.g. in the case of the UK). So, as a precaution, we should be on high alert and implement all possible public health measures to stop this transmission. The Victorian Health Department has the contact tracing and other data, and they are in a better position to assess the situation. We are going through a pandemic and learning new things on a daily basis.   

Mainly, we should boost our vaccination program, which is currently very slow. Without adequate vaccine coverage, we will see these outbreaks in the future as well, and some of them might be devastating. 

We also need to revisit our hotel quarantine policy, as most of the recent cases and outbreaks are due to breaches in hotel quarantine. The cost of designated quarantine facilities will be lower than the cost of lockdowns. It is still not too late to build designated quarantine facilities, as due to slow vaccination globally and the emergence of VOC, we may have to quarantine returning travellers during next year or maybe longer.

Is the Kappa variant in Melbourne different from the variant currently causing issues in India?

B1617.1 [Kappa] in Melbourne is different to the b1617.2 [Delta] variant that was accelerating in India and is starting to increase in the UK. The UK and now the WHO have classed b1617.2 [Delta] as a Variant of Concern now alongside b117 [Alpha], b1351 [Beta] and p1 [Gamma]. B1617.1 [Kappa] is still a variant under investigation.

As outlined clearly by the EU, each b1617 variant (b1617.1, b1617.2 and b1617.3) has distinct mutation profiles and warrants individual assessment. Given the still very limited available data with respect to their transmissibility, disease severity, and immune escape potential relative to other co-circulating SARS-CoV-2 variants in the EU/EEA, the full impact of these lineages on public health is not yet possible to assess. 

Does it have 'faster transmission' than other variants?

In vitro [in the test tube] no, it is not fitter than the variants of concern, in terms of transmission between people, we do not know as the current datasets are limited and spread in the real-world is multi-factorial. From the data in India and also in the UK, one may preliminarily conclude that its genetic cousin b1617.2 [Delta] is fitter [more successful at reproducing] than b1617.1 [Kappa].

What do you make of claims this variant is spreading from 'fleeting' or 'low contact' in ways we haven’t seen before in Australia?

As a group of viruses, SARS-CoV2 continues to surprise us. In July last year, there was a very good study by Australian scientists on transmission in a church during choir singing. This was not the b1617.1 [Kappa] variant but an earlier circulating variant. This highlights how complex transmission in the world can be and there are events that take time to stringently document and understand.

Should people by taking any extra precautions with this variant compared to ‘classic COVID-19’?

There is no longer 'classic COVID-19'. What we have now is a collection of variants circulating that are fitter  [more successful at reproducing] than the earlier variants that were circulating in early 2020. The classification of the variants as variants of concern has been determined by global observations of viral spread. Whilst b1617.1 [Kappa] is not a variant of concern and is presently a variant under investigation, it is prudent we respect all of the variants as potential threats to our health and others.

Vaccination is the most powerful defence we have against this virus and this is a timely reminder that we need to move forward, not only in that space, but also recognise we still have low vaccination rates and thus we need to continue to protect ourselves with the measures we have used so well in 2020.

Fleeting encounters between infected and non-immune individuals can allow aerosolised virus particles to spread from human to human.

Early during the infection cycle, the virus can simply leave the body through exhaled air or upper respiratory tract secretions. So no direct contact is required. These early days, especially when infected people do not show any symptoms or feel sick, can be critical for virus spread to new hosts.

Each person has a thermal plume around their body, dependent on the environment and air drafts in their location. The size of the virus particles or droplets can decrease with drying out conditions. Smaller dried-out particles of viral droplets can be easily breathed in by other people in close proximity.

The study of virus transmission between humans is a difficult science. More research is needed in aerobiology for pandemic infection control.