Generally speaking, "SSRI" is an ideal goal which isn't perfectly realized; all drugs in that class bind "off-target" to proteins other than SERT. In this case

Generally speaking, "SSRI" is an ideal goal which isn't perfectly realized; all drugs in that class bind "off-target" to proteins other than SERT. In this case, fluvoxamine pharmacology is pretty clean and there is experimental evidence only for binding to sigma-1 receptor in addition to SERT (also to a whole bunch of CYP enzymes). Unfortunately the function of sigma-1 is not well understood but it affects calcium signalling in intracellular compartments where covid-19 replicates