An immune system fighting against pneumococcus

Pneumococcus is a common coloniser of the human nasopharynx. However, it can also cause human diseases such as otitis or pneumonia, which may progress into invasive forms such as bacteremic pneumonia, meningitis, or sepsis. This bacterium reaches and establishes itself in the nasopharynx through different mechanisms, which include evasion of the host immune system. Moreover, certain factors such as the coinfection with viruses favour colonisation, as well as the ability of pneumococcus to cause diseases. Our immune system responds to pneumococcal colonisation and infection through the innate and adaptive responses, which can be stimulated by pneumococcal vaccines. In the following article, we will briefly review the mechanisms of pneumococcal infection and how our immune system responds to it; as well as the immune response generated after vaccination and its impact on the prevention of pneumococcal disease.