Face mask mandates return in multiple states as doctors warn of 'quad-demic' of four viral infections

Credit: CC-BY-SA 2.0+ Matti Blume

A quadruple-whammy of viruses are hitting the US as millions go back to work after the holidays, data shows.

Official figures reveal that infections cause by flu, Covid, RSV (a respiratory illness that causes the cold) and norovirus (sometimes called the stomach flu) all started to surge over the Christmas period, when families gathered to celebrate.

And experts say figures will only continue to rise over the coming weeks as the US heads into the peak period of its annual flu season.

Data shows that norovirus cases are at their highest level for this time of year since 2012, while RSV hospitalizations are up nearly 40 percent in two weeks.