Wickham has only played 34 first-team minutes since lasting the full game against Crystal Palace on August 31.
England U21 boss Gareth Southgate said: "Some of the younger ones I want to have a look at because I think they are more likely to be involved going towards a tournament and I would like to bed them in now.
"Connor was not able to report last time and hasn't really played any football since. It is as simple as that, really."
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