Meningococcal disease is caused by Neisseria meningitidis, a bacterium with human carriers as the only reservoir. It is carried in the nose, where it can remain for long periods without producing symptoms.
Despite good access to effective antibiotics, Streptococcus pneumoniae (pneumococci) is still a major cause of disease and death in both developing and developed countries. Pneumococci are the main cause of bacterial respiratory tract infections, such as pneumonia, middle ear infection, and sinusitis, in all age groups.
Haemophilus influenzae type b (Hib) is an obligate human pathogen and an important cause of invasive bacterial infections in both children and adults, with the highest incidence among young children.
Smallpox was once a common, deadly disease, that killed a third of those who contracted it. 200 years ago, it was discovered that vaccination could prevent smallpox. Learn more about the fight against smallpox in our videos
Depending on the level of evidence provided and the methodology used, this advice is typically conveyed through a Guidance, a Systematic review or an Expert opinion.