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Professor Sutton: Origin of Delta variant needs ‘further investigation’

The bombshell piece of information out of Victoria’s press conference has been the revelation by the state’s chief health officer Brett Sutton that another COVID-19 outbreak has been identified in Melbourne.

Genomic testing of members of a family of four who visited Jervis Bay in NSW has revealed they have the Delta variant of the virus. That is a different variant to the other cases which have been linked back to the outbreak from South Australia, which are the Kappa variant.

Professor Sutton said it was not yet clear where the virus had come from, and they have yet been unable to link the virus back to cases in hotel quarantine in Victoria or anywhere else in Australia.

He said it was not out of the question that they acquired the virus while in NSW, or earlier in Victoria.

“Where it’s come from needs further investigation,” said Professor Sutton.

Of some concern, the Delta variant is the variant that has become the dominant strain in India and Professor Sutton said it appeared to be more transmissible than others.

“There are some anecdotal reports of greater illness in children as well as greater increase transmissibility in children we have concerns for that reason.”

It will be interesting to see impact this new discovery has on the discussions around ending or easing Victoria’s lockdown.

What do we know about the Delta strain?

The Delta strain, detected in a Melbourne family who recently went on a road trip to NSW, is the second variant spotted in India – formerly known as B.1.617.2, until it was renamed this week by the WHO.

Unlike Kappa, the variant at the centre of Melbourne’s outbreak, Delta is now considered a variant of concern by the World Health Organisation.

Evidence suggests it is substantially more transmissible than the Alpha variant (already more transmissible than the virus that came out of Wuhan) and is able to slightly reduce the effectiveness of vaccines.

In Britain, the variant has quickly become a major player, quickly outcompeting both the Kappa variant and the well-established Alpha variant, which caused the country’s winter surge. Cases of Delta are rising in the country even as cases of Alpha fall; it now makes up about 75 per cent of the country’s cases.

“It is highly likely that Delta is significantly more transmissible than Alpha,” Public Health England concluded on June 3.

Importantly, human data from Britain suggest both AstraZeneca and Pfizer offer protection against the variant after two doses.

Pfizer’s vaccine is 88 per cent effective against symptomatic disease caused by the variant, while AstraZeneca’s vaccine is 60 per cent effective. Scientists expect both vaccines to offer much higher levels of protection against serious illness and death.

However, there are significant drop offs in effectiveness after only a single dose.