Hospital emergency rooms in California are overwhelmed and pharmacies are running out of the main drug for combating the flu - just one of the hot spots as America experiences a particular nasty flu season.

California health officials say that 27 people younger than 65 have died of the flu in California since October - only three people died of the flu in the Golden State a year earlier.  It's so bad that the emergency room at UCLA Medical Center in Santa Monica saw more than 200 patients during one recent day, mostly because of the flu.  The last time that many people came in for treatment was the deadly 1994 Northridge earthquake.

Pharmacies around Los Angeles have been disappointing people who come in with a prescription for the drug Tamiflu, because it's sold out locally.  There's no national shortage, according to Tamiflu's maker Genentech, so the run on supplies in L.A. suggest a sudden surge in flu cases, known medically as Influenza A virus subtype H3N2.

But it's not just California, outbreaks are reported across the US.  Oregon has had 3,600 confirmed infections, with 123 admitted to hospital.  Flu killed at least three children in Tennessee.  Each state is dealing with a sudden increase in infections.

Federal health officials admit the problem is that this year's flu shot isn't really protecting people from the flu virus.  "It's just one of those years where the (Centers for Disease Control) is seeing that this strain of flu is only somewhat covered by the vaccine," said Jennifer Radtke, manager for infection prevention at the University of Tennessee Medical Center in Knoxville.  "They're seeing that it's anywhere from 10 to 33 percent effective, so anytime there's a mismatch between the vaccine and the circulating strain of the flu, you're going to see more cases."