WASHINGTON (AFP) - The administration of US President Joe Biden announced plans on Thursday to spend US$3.2 billion (S$4.3 billion) to accelerate the development and discovery of antiviral treatments against Covid-19 and future threats.

The plan is called the Antiviral Programme for Pandemics and its funding comes from the American Rescue Plan, a US$1.9 trillion package passed by Congress in March.

"Antivirals are an important complement to existing vaccines, especially for individuals with certain conditions that might put them at a greater risk, for those whom vaccines may not be as protective," Anthony Fauci, the president's chief medical adviser on the pandemic, told reporters.

Antiviral medication can also act as an important line of defence against emerging variants of concern that evade the protective action of current generation vaccines, he added.

The plan will help accelerate clinical testing for oral antiviral pills currently under various stages of development, such as Merck's molnupiravir as well as efforts by Pfizer and Atea-Roche.

The plan is for these to be taken very early after an infection is confirmed, in order to stop the disease from progressing to the severe stage - mimicking what Tamiflu does for influenza.

The other pillar of the programme is seeding the discovery of new antivirals - not just against this coronavirus and its wider family, but other families of viruses that are believed to have pandemic potential.