The covariate is used only in Stage 2's testDESeqANODEV function.
However, Stage 1's negative binomial testDESeq (used for pairwise pre-tests) and Stage 2's negative binomial testDESeq (used for pairwise post tests) does not use the covariate.
Should Stage 2's post test control for covariates?
Is there a reason why the covariates are not controlled in these NB tests?