The adverse outcomes of the combination of respiratory viral infection, especially influenza, and invasive pneumococcal disease is well known. The highest mortality appears to occur when influenza infection occurs concomitantly ie, positive viral cultures, rather than with an antecedent infection (as documented by seroconversion only). The overlap of susceptibility to influenza and pneumococcal CAP in MBL-deficient patients may be a partial explanation for this clinical finding. Staphylococcus aureus is also associated with postinfluenza pneumonia and MBL has demonstrated to be important in protection from S aureus as well.11,12 The very high mortality in community-acquired methicillin-resistant S aureus CAP may partially result from associated influenza infection,13 and may also be more common in MBL-deficient genotypes. Therapeutic options are available for MBL deficiency. MBL replacement during severe acute infections is possible, similar to IV Ig replacement in common variable immunodeficiency. Immunization, both pneumococcal and influenza, of younger MBL-deficient people without other indications is also logical, assuming that they would respond normally to immunization.