What are Covid variants? if it’s more infectious, so why hasn’t it spread widely in Australia?

What do we mean by a variant?

The terminology around viruses can be confusing, and certain terms are still debated among experts. But the general picture resembles a set of nested dolls.

Each strain, said Young, encompasses a number of variants. These variants differ by the set of mutations they contain – in other words the changes in their genome.

The more virulent UK strain of coronavirus is now in Australia but not circulating widely in the community yet — it’s mostly confined to hotel quarantine.

So if this new strain is so virulent, how come we are not seeing more cases cropping up in the community?

The answer involves luck, statistics and the environment, epidemiologists say.

The statistical difference is small

Catherine Bennett, the chair in epidemiology at Deakin University in Melbourne, said statistically there was not much difference between the variants in terms of infectivity.

About 11 per cent of people get infected with the normal strain of coronavirus circulating in Australia.

But with the UK variant, that number is more like 14.7 per cent.

Professor Bennett said when the average person has about 10 or 20 contacts the difference in that percentage only amounts to “one person versus possibly two people.”

Even though the difference is small, it is important to keep the more infectious version out of the wider community, she said.

And the key to doing that is by getting ahead of the curve and testing.

The virus, the host and the environment 

Nancy Baxter, the head of the Melbourne School of Population and Global Health, said there was a complex interaction between the virus, the host and the environment which could influence how the spread of the virus.

She said if, for example, an infected person was doing things mainly outdoors and they weren’t talking a lot and didn’t have contact with other people in a room with air conditioning, they might not transmit COVID-19 as easily.

“If they avoided all those high-risk activities, then in the few days that they were positive in the community, they might not have spread it to someone else,” she said.

She cited the example of the Thai restaurant in the Melbourne suburb of Black Rock where diners got sick just from sitting in a room.

“So luck is a factor. To some degree, we make our own luck, and it’s much better off.

Getting quarantine workers vaccinated must be a priority

Professor Walker said the Federal Government must have a clear plan to ensure that hotel quarantine workers were the “absolute priority” for vaccination.

“That’s the best way to approach these new variants.”