Invasive pneumococcal disease in children with acute lymphoblastic leukaemia.

Area of Science:

• Paediatric Oncology
• Infectious Diseases
• Immunology

Background:

• Widespread use of pneumococcal conjugate vaccines (PCVs) has reduced invasive pneumococcal disease (IPD) in the general population.
• Children undergoing cancer treatment, particularly acute lymphoblastic leukaemia (ALL), may have altered immune responses and remain vulnerable to infections.

Purpose of the Study:

• To assess the incidence, serotype distribution, and clinical outcomes of IPD in children with ALL post-PCV implementation.
• To compare IPD rates in children with cancer against the general paediatric population.

Main Methods:

• A multicentre cohort study was conducted across two tertiary paediatric oncology centres in Australia.
• Data on pneumococcal vaccination status, IPD episodes, serotypes, and clinical outcomes were collected for children with cancer, including a subgroup with ALL.

Main Results:

• 29 IPD episodes occurred in 28 children with cancer (19 with ALL).
• The incidence of IPD in children with ALL was 190-360 times higher than in healthy children.
• Most IPD cases (83%) were caused by non-PCV13 serotypes (e.g., 23B), and additional pneumococcal vaccination uptake was low.

Conclusions:

• Children with ALL have a substantially increased risk of IPD despite PCV use, primarily due to non-PCV13 serotypes.
• Low uptake of additional pneumococcal vaccine doses was observed.
• Optimized vaccination and prophylactic strategies are crucial for this vulnerable paediatric oncology population.