# Comparison of the frequency of viral infections in patients with inborn errors of immunity receiving immunoglobulin by different routes

## TL;DR

This study found that continuous subcutaneous immunoglobulin (cSCIG) may reduce the risk of viral infections in immunocompromised patients during winter compared to other administration routes.

## Contribution

The study provides new evidence that cSCIG is associated with a significantly lower viral infection rate than IVIG and fSCIG in immunocompromised patients during winter.

## Key findings

- The overall viral infection rate was 3.79% across all immunoglobulin administration routes.
- cSCIG had a significantly lower infection rate (2.5%) compared to IVIG (4.2%) and fSCIG (4.4%).
- Adenovirus, influenza A, and human rhinovirus/enterovirus were the most common viral agents detected.

## Abstract

Immunoglobulin replacement therapy (IRT) is the primary treatment for immunocompromised patients and can be administered via intravenous, subcutaneous, or facilitated subcutaneous routes. In this study, our objective was to compare the incidence of viral infections among patients receiving IRT via different administration routes during the winter season. Fifty-eight patients with primary immunodeficiency (PID) receiving immunoglobulin replacement therapy (IRT) were enrolled in the study. Patients were monitored for their immunoglobulin (Ig) levels, nasal swabs were studied with PCR monthly, and any viral infections were documented. The study included 58 patients with PID, with 33 males (56.8%) and 25 females (43.1%). The median age of the patients was 17 years (IQR, 28.5), and the median age at diagnosis was 11.5 years (IQR, 25.5). The most common IRT route was IVIG, used by 55.1% (n = 32) of patients, followed by cSCIG 27.5% (n = 16), and facilitated subcutaneous immunoglobulin (fSCIG) 17% (n = 10) of patients. The overall frequency of viral infections was 3.79%, distributed among IRT routes as follows: IVIG (n = 32, 4.2%), cSCIG (n = 16, 2.5%), and fSCIG (n = 10, 4.4%). The infection rate in the cSCIG route was significantly lower than in the IVIG and fSCIG routes (p < 0.05). The most common viral agents were adenovirus (21.8%), influenza A (16.4%), and human rhinovirus/enterovirus (16.4%). Conclusion: In a 3-month evaluation of patients, the infection rate was lower in the cSCIG route compared to the other IRT routes. cSCIG is a safe and viable treatment option that can effectively improve the quality of life for immunocompromised patients.
What Is Known:• Immunoglobulin replacement therapy (IRT) is the standard treatment for patients with primary immunodeficiencies (PID), aiming to prevent infections by maintaining adequate serum immunoglobulin levels. Limited research exists regarding the impact of IRT on the prevention of viral infections.What Is New:• This study reveals key insights into viral infections in PID patients receiving immunoglobulin replacement therapy (IRT) during winter. The overall viral infection rate was 3.79%, with IVIG at 4.2%, cSCIG at 2.5%, and fSCIG at 4.4%. Notably, the cSCIG group had a significantly lower infection rate than the IVIG and fSCIG groups (p0.05). These findings suggest that cSCIG may lower the risk of viral infections in PID patients during high-risk winter months.

What Is Known:

• Immunoglobulin replacement therapy (IRT) is the standard treatment for patients with primary immunodeficiencies (PID), aiming to prevent infections by maintaining adequate serum immunoglobulin levels. Limited research exists regarding the impact of IRT on the prevention of viral infections.

What Is New:

• This study reveals key insights into viral infections in PID patients receiving immunoglobulin replacement therapy (IRT) during winter. The overall viral infection rate was 3.79%, with IVIG at 4.2%, cSCIG at 2.5%, and fSCIG at 4.4%. Notably, the cSCIG group had a significantly lower infection rate than the IVIG and fSCIG groups (p0.05). These findings suggest that cSCIG may lower the risk of viral infections in PID patients during high-risk winter months.

The online version contains supplementary material available at 10.1007/s00431-025-06201-w.