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It’s been a recurring theme in the pandemic: just when we think we’re on top of an outbreak, COVID-19 rears its ugly head and makes things complicated. This time it’s a subvariant of the Delta strain coupled with waning immunity causing cases to spike abroad. 

So just how serious is it? 

What we know so far

The new subvariant AY4.2 accounted for about 6% of sequenced COVID cases in the UK by late September and has also emerged in the United States, Israel, India, Japan, China, Russia and parts of the European Union. It’s yet to be classified as either a variant of interest or a variant of concern by the World Health Organization, although the UK has declared it a “variant under investigation”. The Israel Health Ministry has found it may be 15% more contagious than the original Delta variant but so far doesn’t appear to be more deadly. 

Each person who catches COVID has a slightly different mutation of the virus, which we know through genome sequencing. Once these mutations are large enough to affect how transmissible or how deadly the virus is, or how the virus functions, it’s deemed a new variant. 

The difference between Delta and Delta-plus is minor, distinguished by two mutations on the virus’ spike protein, which connects with the surface of human cells. One of the reasons COVID-19 is more transmissible than other coronaviruses like SARS is because these proteins shift shape easily to better connect with the cell, and have a tighter grip. 

University of Queensland infectious disease specialist Paul Griffin tells Crikey knowing the impact mutations had on the virus was tough. 

“We don’t always know how mutations change the properties of the virus, and with this new subvariant we really need more information,” he said. “[Delta-plus] does have some properties that need to be observed, and we need to keep monitoring it.”

What impact is it having abroad? 

Hospitalisations in the UK have increased dramatically in the past few weeks, putting strain on the healthcare system. There have been more than 1000 daily hospitalisations, and deaths rose by 25%. Hospitalisations have increased from about 100 in June (though down from an all-time high of nearly 4000 in January before wide vaccine uptake). 

While there are concerns this is due to Delta-plus, there are a variety of factors at play. 

The UK opened up much more quickly than Australia, with huge “Freedom Day” celebrations. Mask mandates were removed as were capacity restrictions. It was also months ahead in its vaccine rollout, meaning immunity from the vaccine is starting to wane. While boosters are available, uptake has been low. 

With just a handful of AY4.2 cases abroad, the impact of the subvariant is yet to be seen. 

Are boosters on the way? 

Griffin says the new variant isn’t yet a cause for alarm in Australia. 

“We need to look to other countries to make sure we don’t make the same mistakes, and our situation is vastly different so we shouldn’t expect the same thing,” he said. 

But boosters are important. Third doses are available for the severely immunocompromised, with a wider rollout expected to begin from next month following advice from the Australian Technical Advisory Group on Immunisation and the Therapeutic Goods Administration.

Australia is also planning to manufacture mRNA vaccines onshore, though we don’t yet have the facilities or capacities. An announcement on which companies will be in charge of developing the vaccines is expected within weeks.