Health and Human Services Secretary Tom Price was too busy racing to get his flu shot to address the flak over him chartering private flights with taxpayer money.

President Trump says he's not happy and plans to look into claims Price ripped off taxpayers. We got him in D.C. and asked if he was worried about hearing Trump's tagline ... "You're fired."

The HHS Sec. has since apologized, saying he won't take private charters anymore, and will reimburse the expenses for the ones he's already taken. Still, you can tell Price was already feeling the heat, and used the flu to evade questions.

It worked here ... probably won't fly in the Oval Office, though.