Epidemiological and mechanistic studies on the role of pneumococcal conjugate vaccine in antimicrobial resistance in Laos

PCVs prevent pneumonia and invasive pneumococcal disease (IPD). The serotypes contained within PCV are those which carry most antimicrobial resistance (AMR). PCVs reduce the carriage of PCV serotypes, and also limit the use of antibiotics by preventing pneumococcal infections. In the US, the 13-valent PCV (PCV13) reduced childhood IPD AMR by >75%. Despite a high pneumonia burden in Asia, very few countries have adopted PCV into their national immunisation programs. PCV may have a substantial role in reducing AMR and it is vital that the role of PCV in reducing AMR in this region is determined. PCV introduction has also led to serotype replacement with serotypes that are not included in the vaccine (NVTs). It is therefore important to define pneumococcal population changes and identify emergent clones in the post-PCV era. In 2013, we commenced pneumococcal carriage surveillance in Laos in children aged 2- 59 months with acute respiratory infection (ARI). Our study in Laos will: a) determine the PCV13 effectiveness against AMR in pneumococcal carriage isolates; b) determine the AMR and virulence of emerging NVTs; and c) investigate using a life-like system the recombination frequency for the acquisition of resistance genes, and secondary chromosomal insertions, in pneumococcal NVTs.