Flu shot before trip to LA?

Heard that the influenza situation is pretty bad right now, how is it like in LA and San Diego? I am from the UK and will be travelling to San Diego on the 21 Mar for a week to attend a huge conference with lots of people and then a couple of days in LA. It takes typically 14 days after the flu vaccine for the protection to develop so I am wondering if it is too late and not much point for me to get the jab in the UK now before flying. Also, is wearing a face mask a practice in LA? I am thinking to wear one but also wouldn’t want to be the odd one out. Thanks!