PNEUMOCOCCAL SEROTYPES IN INFANTS LESS THAN 90 DAYS OLD BEFORE AND AFTER INTRODUCTION OF PNEUMOCOCCAL CONJUGATE VACCINE (PCV) IN BLANTYRE, MALAWI
Malawi introduced PCV13 into its Expanded Program on Immunization in November 2011. Our aim was to describe the change in serotype distribution causing invasive pneumococcal disease (IPD) in neonates and young infants in Blantyre, Malawi.
We conducted a retrospective study of IPD in infants aged <90 days admitted to Queen Elizabeth Central Hospital (QECH) in Blantyre, Malawi between 2005 and 2018. IPD was defined as culture-confirmed Streptococcus pneumoniae from blood or cerebrospinal fluid, collected when clinically indicated. Serotype was determined by Latex agglutination.
We identified and serotyped samples of 130 cases of IPD. Results show that overall, serotypes 5 (19%), 1 (11%), 7F (5%), 6A/B (3%), and 23F (3%) were most common in this population over the time period studied. Non-vaccine serotype (NVT) accounted for 19% of cases and 40 samples were not typeable. Serotypes 5 and 1 were the predominant cause of IPD before as well as after PCV13 introduction.
Overall IPD cases have been on the decline in this population. Vaccine-type serotypes were the main cause of IPD in neonates and young infants, both before and after PCV13 introduction. Vaccine strategies should be considered to optimise the potential for reducing VT-IPD in this setting among this vulnerable population.