Optimising immunisation in children with 22q11 microdeletion

Vaccine immunity in patients with 22q11.2 microdeletion syndrome

BACKGROUND

Patients with microdeletion 22q11.2 syndrome (MDS) exhibit immunological defects, characterized by abnormalities in the development of the thymus, which plays a crucial role in T-cell maturation and immune response. As a result, these patients may have impaired adaptive immunity, with decreased responses to vaccination.

METHODS

This was a prospective observational study. Vaccine serology (tetanus, diphtheria, Haemophilus influenzae type b for children <5 years, measles, varicella, hepatitis A and B, and SARS-CoV-2) and immune parameters were assessed in MDS patients aged between 1 and 25 years followed in Geneva between February 2022 and April 2023.

RESULTS

41 MDS patients were included. The median age was 13 years old. Most of them reported recurrent otitis and bronchitis up to 10 years, and a mild COVID-19 disease in the past. Immunological work-up indicated normal immunoglobulin levels and lymphocyte counts for the majority. Most patients were well vaccinated for tetanus, diphtheria, Haemophilus influenzae type b and measles, but only half were fully vaccinated for hepatitis B, and SARS-CoV-2 and only a quarter for hepatitis A. 70% of the patients had received 3 doses of pneumococcal conjugate vaccine in infancy but only a minority an additional dose. While most of them were seroprotected against tetanus, diphtheria, and Hib, a substantial number lacked seroprotection against varicella, measles, hepatitis B, and pneumococcus.

CONCLUSION

This study suggests that regular assessment of antibody levels for measles, hepatitis B, varicella, and pneumococcus, regardless of vaccination status should be encouraged in MDS patients, with reimmunization according to vaccine serology, to enhance vaccine immunity.

Evaluation of rotavirus vaccine administration among a 22q11.2DS patient population

Background

22q11.2 Deletion Syndrome (22q11.2DS) can result in array of congenital abnormalities including immune dysfunction. International guidelines recommend immune evaluation of 22q11.2DS patients prior to live vaccine administration. A rotavirus vaccination program for infants aged 2 and 4 months was implemented in British Columbia (BC) in 2012. Adherence to immune workup recommendations prior to 2 months of age in patients with 22q11.2DS and adverse events following immunization is not known.

Methods

A retrospective chart review of children diagnosed with 22q11.2DS in BC from January 1, 2012 to January 1, 2019 was conducted. Demographic, clinical, laboratory, immunization data and adverse reactions to vaccines were obtained. International guidelines were used as a reference for adherence to immunologic workup recommendations.

Results

Forty-two children with 22q11.2DS were included. Immunization records were available for 39 children, and 22 (52.3%) received at least one dose of a live rotavirus vaccine. No adverse events following immunization were noted in clinical records. While 25 out of 27 (92.6%) of patients who received an immunological workup had a CD4 + lymphocyte count to qualify for safe administration of a live vaccination, only 12 (44%) received the Rotavirus vaccine. Of 22 infants diagnosed with 22q11.DS prior to 8 weeks of age, only ten (45.5%) received an immune workup before the rotavirus vaccine.

Conclusions

The majority of our infant cohort did not receive medical care consistent with international 22q11.2DS vaccination and immunological surveillance recommendations. More effective dissemination of 22q11.2DS guidelines and improved immunological assessment for infants with 22q11.2DS in BC is necessary.