# Preliminary Case–Control Study of Antibody Response to Vaccines in Children on bDMARDs

## TL;DR

The study finds that some children on bDMARD therapy have low or declining antibody levels for hepatitis B and measles, suggesting the need for regular monitoring and vaccination strategies.

## Contribution

This work provides novel pediatric data on vaccine responsiveness under biologic therapy and emphasizes the importance of routine immunological monitoring.

## Key findings

- A subset of patients had low baseline hepatitis B and measles antibody levels before bDMARD therapy.
- Measles antibody levels declined in some patients during follow-up, while pneumococcus and hepatitis B levels were mostly preserved.
- Regular screening and tailored vaccination strategies are recommended to maintain immunity in immunosuppressed children.

## Abstract

What are the main findings?

A subset of patients exhibited low baseline hepatitis B and measles antibody titers even before the initiation of bDMARD therapy.

During follow-up, a measurable decline in measles antibody levels was observed in a small number of patients, while protective titers for pneumococcus and hepatitis B were largely preserved.

What are the implications of the main findings?

The study highlights the importance of screening vaccine antibody levels before and during bDMARD therapy to detect children at risk of waning immunity.

Implementing tailored vaccination and timely booster strategies—particularly for measles and hepatitis B—may enhance long-term protection in immunosuppressed pediatric patients.

This work contributes novel pediatric data on vaccine responsiveness under biologic therapy, emphasizing the need for routine immunological monitoring in clinical practice.

Background/Objectives: Patients with rheumatic diseases have an increased burden of infection owing to biological disease-modifying antirheumatic drug (bDMARD) therapy. Therefore, vaccination is crucial for the prevention of infection in these patients. In this case–control study, we aimed to evaluate vaccine response to hepatitis B, pneumococcus, and measles using antibody titers in patients undergoing biological therapy. Methods: This study included 16 patients aged 5–18 years of age who received bDMARD treatment and 20 healthy controls. Serum samples of the patients were collected at baseline and subsequently on the 3rd and 6th months after bDMARD therapy, and IgG antibodies against pneumococcal capsular polysaccharide antigen (PCP), measles, and hepatitis B were measured. Results: There were no statistically significant differences in mean anti-HBsAg, anti-PCP, and anti-measles antibody titers between the study and control groups. The percentages of patients with anti-HbsAg, anti-PCP, and anti-measles protective antibodies were 68.8% (n = 11/16), 100% (n = 16/16), and 56.25% (n = 9/16), respectively. There were no statistically significant differences in the mean antibody titers at baseline and 3rd month. Only the anti-measles IgG titer level decreased below 200 (mIU/mL) in one patient in the 3rd month and in two patients in the 6th month. Conclusions: Patients with low or declining hepatitis B and measles antibody titers before or during bDMARD treatment may require close monitoring to ensure adequate protection against vaccine-preventable diseases. Regular screening and follow-up are essential in this patient population.