Pneumococcal polysaccharie vaccine (PPV), also known as Pneumovax, is a vaccine used to prevent Streptococcus pneumoniae (pneumococcus) infections such as pneumonia and septicaemia. PPV is not the same vaccination as the pneumococcal conjugate vaccine (PCV) that is routinely administered to infants in the US, Canada, and the UK. See further under Children, below.