. 2023 Jan 17;43(2):247–270. doi: 10.1007/s10875-022-01418-y

Table 4.

Guideline recommendations^a for live vaccine administration (MMR and varicella) in 22q11.2del at age 12 months

Laboratory results (blood)	Comment
1. CD4 $\geq$ 400 cells/mm³ (absolute)	Recommended
2. CD8 $\geq$ 200 cells/mm³ (absolute)	Recommended
3. Tetanus IgG protective (3 + weeks after dose 3) †	Recommended
4. CD45RA⁺CD3⁺/4⁺ % > CD45RO⁺CD3⁺/4⁺ %	Utilize data from earliest assessment
If available and T cell numbers abnormal, consider either confirmation of normal TREC assay result on NBS or flow cytometry confirming RTEs (CD31)	When available, either marker of RTEs can help confirm adequate thymic function AND helps rule out most causes of SCID

^aSome experts may recommend immunizing individuals in certain situations who may not meet each of the above criteria. RTE, recent thymic emigrants

^†Assessment of hepatitis B IgG surface antibody may serve as a reasonable alternative if tetanus IgG assay is not available