Patterns of spike-specific IgG subclasses after different types of COVID-19 vaccines in patients with hereditary angioedema due to C1 inhibitor deficiency.

Objectives

Different forms of vaccines have been introduced to reduce hospitalizations and prevent the risk of serious coronavirus disease 2019 (COVID-19). Monitoring of the SARS-CoV-2 spike-specific IgG subclasses after COVID-19 vaccinations will provide additional details about specific long-term immune memory in patients with hereditary angioedema due to C1 inhibitor deficiency (HAE-C1INH).

Methods

We examined four HAE-C1INH patients vaccinated with primary vector (Sputnik), mRNA-based (Pfizer-BioNTech), or inactivated (Sinopharm) vaccines and one booster mRNA-based vaccine in the Hungarian Angioedema Centre of Reference and Excellence. The levels of each spike-specific IgG subclass and the total spike-specific IgG were determined by in-house ELISA. Total serum IgG and IgG subclasses were measured by nephelometry.

Results

Patient 1 who was infected after mRNA-based vaccination had high spike-specific IgG4 to total spike-specific IgG ratio (41 %). Two patients who had vector-based vaccination without infection and the patient with inactivated vaccination had low spike-specific IgG4 to total spike-specific IgG ratios. The patient with slightly higher total serum IgG4 has also had high total serum IgG4 before the COVID-19 pandemic.

Conclusion

Taken together, our study was an individual-level observation, where spike-specific IgG4 antibody response appeared several months after mRNA-based SARS-CoV-2 immunization in a HAE-C1INH type I patient. Further investigations are planned to examine the in vitro complement activation of spike-specific IgG4 after mRNA-based vaccinations.