JAK3 and viral infectious disease: Thus, treatment with either tofacitinib or baricitinib has been associated with increased risk for cytopenias (albeit of mild degree), viral infections (especially from VZV) and increases in serum lipids, which are all related to JAKs blockade (e.g. viral infections due to dampened IFNα/JAK1 and/or JAK3/NK-cells axis, cytopenias due to dampened JAK3/myelopoiesis axis etc.).37, 42