Adenosine deaminase (ADA) - the gene product inhibited by the Spartan virus - is an actual enzyme. Hereditary defects in the enzyme can lead to a condition known as Severe Combined Immunodeficiency (SCID), which leaves patients at risk for severe infections like those depicted. A treatment for the condition is to introduce a functional immune system into the patient via bone marrow transplant like Scully suggests for Mulder.
Creator Chris Carter declared that as My Struggle (2015) is about Mulder's struggle, "My Struggle II" is about Scully's.
This is the only appearance of former series regular Monica Reyes in season 10.
The character Tad O'Malley is based on conspiracy theorist and radio host Art Bell, who appeared as himself in Chris Carter's Collateral Damage (1999).
Co-writer Anne Simon is the show's science advisor and has been with the series since the first season.