Highlights
- 180 million people have now been infected with the virus at some stage, while the global death toll is rapidly approaching four million.
- Research from Public Health England estimates Delta has a reproductive value of six, compared to between two to three from the other mutated variants.
- Both Professors Bennett and Booy are urging Australians to be vaccinated, explaining that the AstraZeneca and Pfizer vaccines are highly effective against the variants if people are fully vaccinated.
It has been 18 months since COVID-19 began to grab the world’s attention, quickly spreading from the Chinese city of Wuhan before infecting and killing millions, and overwhelming health systems in all corners of the globe.
During this time the virus has not only spread, it has mutated multiple times. There are now several variants of the original COVID-19 strain that are more transmissible, with the Delta variant predicted to soon be the world’s dominant variant.
Professor Catherine Bennett from Deakin University:
"It seems to have a particular mutation or set of mutations that impact its ability to transmit. So it's a variant that we've been watching because we have seen it out-compete the other variants of concern. So Alpha, the variant associated with the UK originally, has been quite quickly replaced by this Delta variant as the dominant strain.
This particular variant is potentially 60 per cent more infectious than we saw with the Alpha variant and that already was 50 per cent more infectious that other variants. So its ability to transmit is a concern."
The Delta variant, first identified in India, has now been reported in at least 80 countries.
It now makes up 99 per cent of new infections in the United Kingdom, and 90 per cent in Russia.
According to Public Health England research, for every one person infected with Delta, six other people will catch the virus.
Professor Bennett says the Alpha variant was becoming the dominant variant in Australia, but it has been overtaken by Delta.
“We were seeing (Alpha) being brought in with returning travellers. But now whether it's people from Asia, Europe or North America the chances are it's going to be a Delta variant if they do happen to be positive. So I think we have to get used to the fact that Delta will be the dominant global variant, and that's the one we really need to be focused on.”
In Australia, there have been multiple outbreaks of COVID-19 that can be traced back to the Delta or Alpha variant.
While Delta is quickly becoming the country's dominant variant, there are also warnings about the Kappa variant, also known as the ‘other’ variant that was first identified in India.
Professor Robert Booy ((BOY)), infectious diseases specialist with the University of Sydney and the Immunisation Coalition, explains its origins.
"Several months ago people noticed that there was a mutant strain developing in India. They called it a double mutant, but indeed there was probably a dozen mutations that led to this new variant. And it was called B1.6.17, two teenagers, so you could call it the 'teenage mutant ninja twosome'."
COVID-19 is caused by an RNA virus, the same virus which causes influenza.
Professor Booy explains that RNA viruses tend to mutate “very easily”, which explains the high number of COVID-19 variants - of which there are several others, like the Beta and Gamma variant, wreaking havoc overseas.
“COVID-19, like influenza, doesn't copy itself very well at all, so the progeny, the babies of one virus, can be slightly different, mutated from the original virus .Viruses want to survive just like how you and I want to survive, and so although they don't have volition, they can't make a decision.
The viruses that do survive are those that can transmit, so in mutating those that are able to transmit from one person to another and on and on are those that become entrenched in the community.”
Professor Bennett adds that data from the UK shows that 83 per cent of cases of Delta are in people who are not vaccinated, with fewer than four per cent of cases coming from people who were fully vaccinated.
