Low IgG trough and lymphocyte subset counts are associated with hospitalization for COVID-19 in patients with primary antibody deficiency

IgGRT has been shown to modulate T-cell immunity and diminish proinflammatory responses of monocytes in common variable immune deficiency (CVID).2,3 A case report on clinical outcomes of a CVID patient with COVID-19 postulated benefit of both high-dose intravenous immunoglobulin treatment and/or compliance with IgGRT in reducing the severity of COVID-19.4 A study on cellular and humoral immune responses of 2 patients with CVID on IgGRT who presented with mild to asymptomatic COVID-19 showed robust CD4+ T-cell responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), but 1 of the patients failed to mount SARS-CoV-2–specific antibody response.5 Well-established risk factors for COVID-19, including age and comorbidities, could also influence the outcome of COVID-19 in these patients.6 However, the function of IgGRT on modulation of cellular immunity and inflammation suggests a possible role for IgGRT in the outcomes of COVID-19 for these patients with PAD.2,3 Here, we investigated the clinical and immunologic characteristics of patients with PAD on IgGRT, in relation to their clinical outcomes of COVID-19, assessed by the hospitalization. From this cohort, 56% (n = 13) of patients met the criteria for CVID and 43% (n = 10) of patients met the criteria for other PADs (Table I).7 Protective titer pneumococcal polysaccharide vaccine was defined as titer greater than or equal to 1.3 μg/mL in this study (see Table E1 in this article’s Online Repository at www.jaci-inpractice.org).7 However, given the lack of consensus on defining protective antibody response, we also included a lower threshold considered protective against invasive pneumococcal disease defined as titer greater than or equal to 0.35 μg/mL (Table E1).8 Criteria for diagnoses of CVID and other PADs are described in this article’s Online Repository’s Methods section at www.jaci-inpractice.org.7 Available laboratory data were compared between patients who were hospitalized and those managed as outpatients. Next, we compared the well-established comorbidities associated with poor outcome of COVID-19 between hospitalized and nonhospitalized PAD patients with COVID-19.6 Frequencies of lung disease, autoimmune disorder, malignancy, use of immunosuppressive therapy, hypertension, coronary artery disease, diabetes mellitus, obesity, chronic kidney disease, smoking, and congestive heart failure (CHF) were compared.6 Of these, hospitalized patients presented with a significantly higher frequen