US infectious disease expert Anthony Fauci said on Tuesday that while the Delta variant of the coronavirus is the cause of more than 80% of new US COVID-19 cases, the authorised vaccines remain more than 90% effective in preventing hospitalisations and deaths, as reported Financial Post.

Fauci added that the US Centers for Disease Control and Prevention is reviewing data from multiple groups of vaccinated people to determine how long protection from COVID-19 vaccines lasts and will use that information to determine the potential role of booster doses.

Meanwhile, Janet Woodcock, the acting director of the FDA, suggested that states should continue to hold onto their inventories of unused vaccines as manufacturers are working to determine the shelf life of their doses.