mRNA vaccine boosting enhances antibody responses against SARS-CoV-2 Omicron variant in patients with antibody deficiency syndromes

ABSTRACT

Patients with primary antibody deficiency syndromes (PAD) have poor humoral immune responses requiring immunoglobulin replacement therapy. We followed PAD patients after SARS-CoV-2 vaccination by evaluating their immunoglobulin replacement products and serum for anti-spike binding, Fc{gamma}R binding, and neutralizing activities. Immunoglobulin replacement products had low anti-spike and receptor binding domain (RBD) titers and neutralizing activity. In COVID-19-naive PAD patients, anti-spike and RBD titers increased after mRNA vaccination but decreased to pre-immunization levels by 90 days. Patients vaccinated after SARS-CoV-2 infection developed higher responses comparable to healthy donors. Most vaccinated PAD patients had serum neutralizing antibody titers above an estimated correlate of protection against ancestral SARS-CoV-2 and Delta virus but not against Omicron virus, although this was improved by boosting. Thus, currently used immunoglobulin replacement products likely have limited protective activity, and immunization and boosting of PAD patients with mRNA vaccines should confer at least short-term immunity against SARS-CoV-2 variants, including Omicron.