When, if at all, is it more appropriate to use http over web sockets?

I am using Socket.IO with a MEAN stack and it's been excellent for low latency and bidirectional communication, but what would be the major draw back for using it for relatively static data as well as dynamic?

My assumption is that it would be more apt for sending more dynamic content. That being said, once a socket connection is established, how relevant is the amount of communication being done? Is there a time where it would be more appropriate to use http instead when a connection is constantly established throughout the user's direct interaction with the application?

Thanks!