The number of flu cases is spiking here in the St. Louis metro area and across the country.

The CDC says the flu is now spreading in 46 states, including Missouri and Illinois. That's up from 40 states less than a week ago.

Here in the St. Louis area, emergency rooms are seeing an increase in flu cases. Doctors worry it could get even worse in the next few days.

Once it gets going, doctors expect this flu season to run for about eight weeks.

It takes two weeks for a flu shot to kick in, but doctors say if you haven't gotten your shot already, it's not too late.