Where can I get a flu shot if I’m out-of-network?

I was turned away at CVS and Walgreens because apparently it’s out-of-network (from New England) and they don’t accept co-pays for vaccination there. I work tough hours M-F but was wondering where I can find a place to get a flu shot even if I can just throw a copay? I’m getting stressed about it and having issues finding good info on it.