Worst case is 2800 daily winter Covid-19 cases

Cases in Australia could surge to more than 1300 infections a day as winter approaches — more than double the peak of last year.

Anne Hyslop receives an AstraZeneca vaccine in Melbourne on Wednesday. Picture: AFP

COVID-19 cases in Australia could surge to more than 1300 new infections a day as winter approaches — more than double the peak reached last year — according to the “most likely to happen” estimate from an advanced coronavirus model used by the US government.

On a “worst case” scenario, where vaccination programs remain ineffective, forecasts by the Institute of Health Metrics and Evaluation at the University of Washington predict cases in Australia will increase from around zero to more than 2800 a day by the start of July.

“These IHME forecasts are some of the best you can get,” said Dr Benjamin Ryan, an Australian and public health expert at Baylor University, Texas.

“I don’t know how Australia gets out of this situation without a surge in cases at some point; the evidence is increasingly that at some point you have to reach herd immunity,” he said.

The forecasts, updated on April 1, predict infections, deaths and hospital utilisation across different countries and US states based on the observed impact of the virus, its seasonality, vaccination levels and likely policy responses by governments.

“Given the high mobility, low use of masks, and seasonal pattern starting to work against Australia, we would expect a higher number of COVID cases there,” said Theo Vos, a professor of health metrics at the University of Washington.

Australia and New Zealand were unusual countries because most of their cases were “imports not home grown infections”, he cautioned, suggesting maintenance of strict border control to reduce the chance of a major outbreak.

The updated IHME forecasts, which the Trump administration had used to advocate lifting COVID restrictions early last year, come as the federal government faces growing criticism for the slow pace of the vaccine rollout and ongoing disruption from “snap” lockdowns in state capitals.

“There will need to be some tough decisions very soon about what number of COVID cases in the community are acceptable if Australia wants to re-open borders. When will it be safe enough?” Dr Ryan said.

About 920,000 Australians have been vaccinated so far, less than a fifth of the target the government set in February.

Dr Ryan said “zero COVID” wasn’t a realistic strategy in Australia unless the government wanted to keep the international border permanently closed.

“To avoid this scenario Australia would need to vaccinate 70 per cent to 85 per cent of its population including children, which will be very difficult,” he added.

International travel with New Zealand resumed this week but restrictions on travel with other nations aren’t expected to be lifted until 2022.

“There are sad stories of people being kept out of the country, but it is precisely those measures that are keeping things so nicely under control in Australia and New Zealand,” Professor Vos said.

Dr Ryan said Texas, which controversially lifted all restrictions last month, offered the best model for Australia to “live with the virus”.

“Hospitals in central Texas were able to continue providing care for the entire community during the winter surge.

“Now all the restrictions are gone pretty much and things are getting back to normal,” he added.