Plans for one-shot Covid/flu jab in Australia

Australians could have access to a single vaccine for Covid-19 and influenza by 2024 as clinical trials are set to begin.

The combined shot for flu, Covid-19 and respiratory virus RSV is in early testing stages, with trials to start later this year, Moderna chief medical officer Paul Burton says.

Dr Burton expects combined vaccines will be key to fighting respiratory diseases in the aftermath of the pandemic, and to adapt to multiple strains within one season.

"We still have to be cautious, this fight is not over and we can't let our guard down," he told Sky News on Monday.

Mr Burton said bringing vaccines together and adapting will be the future, as we think about diseases other than Covid-19.

Meanwhile, Australia's multibillion-dollar mRNA manufacturing hub will be bigger than initially expected.

The first of its kind in the southern hemisphere, the facility was announced in March by the Morrison government as part of an agreement with Moderna.

Finding a location has reached its final stages and a site will be announced in a few weeks, Moderna general manager Michael Azrak said.

"It's taken a little bit longer than we anticipated because we're actually going to be building a larger facility than we anticipated," he told Sky News.

The pharmaceutical giant aims to break ground on the Victorian site before the end of the year, Mr Azrak said.

It will be operating by the end of 2024, subject to approval by the medicines regulator.