Can you be fired for not showing up while sick even if you give a heads up and try to get your shift covered?

For some context, my friend has been throwing up all day and has no one who can take her shift. She’s worried about being fired for it, which is bullshit because she’s a server so there is no reason she should be even allowed to work while throwing up because of like food safety and all that. She was also in the hospital last night. I was wondering if there was any action she could take if they did decide to try to fire her, am I figured this was the best sub to ask about it. Thanks.