Why Covid 2.0 is less deadly: all that sanitising bought us time

Something incredible is happening in those unpleasant nose swabs: coronavirus is becoming less deadly as time goes on.

CSIRO chief executive Larry Marshall. Picture: Kym Smith

Is COVID-19 becoming less ­deadly as the pandemic pro­gresses? That’s a question being asked by scientists who have found the amount of virus present in throat and nose swabs from positive ­patients is less than what it was at the start of the pandemic.

There are now understood to be a number of different strains of the SARS-CoV-2 virus circulating around the world, and a US study in Detroit — which took samples from hospital patients in Michigan from April to June — shows the initial viral load in COVID-19 swabs has been decreasing as the pandemic progresses.

The study found that the downward trend in the viral load on swabs was associated with a decrease in the death rate.

It also suggests Australia’s ­approach of rapid social-distancing measures, lockdowns and the use of masks may have decreased exposure and consequently bought time for the population as the virus became less deadly.

Researchers at Australia’s peak science organisation, the CSIRO, are analysing global data to fast-track our understanding of the different strains of the virus and how they are evolving.

CSIRO chief executive Larry Marshall said knowing the genetic code was vital in combating the virus.

“The more we know about this virus, the better armed we’ll be to fight it,” he said.

The World Health Organisation said the death rate of the virus at the start of the pandemic was approximately 1 per cent, but Australia’s rate has stayed closer to 0.4 per cent, which has ­ resulted in 905 deaths.

Learning more about how the virus evolves and its different strains may hold the key to understanding both mortality rates and how to fight it.

CSIRO’s bioinformatics team leader Denis Bauer said as the virus evolved, its blueprint ­became increasingly important because it held instructions about the behaviour of the virus.

“Globally, there are now a huge amount of individual virus sequences,” Dr Bauer said.

“Assessing the evolutionary distance between these data points and visualising it helps ­researchers find out about the different strains of the virus, including where they come from and how they continue to evolve.”

The author of the US study, Said El Zein from the Wayne State University/Detroit Medical Centre, said there was evidence to suggest a link between “initial viral load and mortality”.

“A downward trend in the ­initial (viral load) may reflect a ­reduction in the severity of the pandemic, and trends in the virtual load values over time represent a marker to assess the progress of the pandemic,” Dr El Zein said.