Background

The introduction of PCV7 in August 2009 and PCV13 in May 2011 in The Gambia resulted in decline of invasive pneumococcal disease (IPD) incidence by 55% in the Eastern region although changing serotypes are emerging.

Methods

We retrospectively compared disease and serotype prevalence pre-PCV (January 2005-December 2009) and post-PCV (January 2012 - December 2015) periods for IPD in the Western region of the country

Results

Out of 12,454 blood and 979 CSF cultures analysed, 6.8% (847/12454) blood and 6.9% (68/979) CSF were clinically significant pathogens. The prevalence of IPD for suspected bacteraemia was 1.8% (218/12454) constituting 25.8% (218/846) of all confirmed cases and 3.9% (38/979) for meningitis constituting 55.9% (38/68). When compared by vaccine period, a significant drop across all age groups post-PCV was found, decreasing from 32.4% (160/494) to 16.5% (58/352) for bacteraemia and from 67.3% (33/49) to 26% (5/19) for meningitis.

Serotype data was available for 86.3% (221/256) and decrease in PCV13 vaccine serotypes from 62.2% (120/193) to 41.3% (26/63). Concurrently increase in non-vaccine serotypes from 24.9% (48/193) to 42.8 % (27/63) was found with 12F accounting for 50%.

Conclusions

The PCVs have reduced IPD but serotype replacement is noted warranting surveillance and more intervention.