On April 6, CDPH released recommendations and provided education to clinics and health care facilities to administer MMR vaccine to any patients or health care workers without evidence of immunity,§ reinforce infection control measures, and offer a third MMR dose to persons living with HIV infection whose CD4+ counts were ≥200 cells μL3 because of initial concern for increased risk of complications (4–6). Here, CD4 is linked to HIV infectious disease.