In adults, Neisseria meningitidis and Streptococcus pneumoniae together cause 80% of bacterial meningitis cases. Risk of infection with Listeria monocytogenes is increased in persons over 50 years old. The introduction of pneumococcal vaccine has lowered rates of pneumococcal meningitis in both children and adults.Recent skull trauma potentially allows nasal cavity bacteria to enter the meningeal space. Similarly, devices in the brain and meninges, such as cerebral shunts, extraventricular drains or Ommaya reservoirs, carry an increased risk of meningitis. In these cases, the persons are more likely to be infected with Staphylococci, Pseudomonas, and other Gram-negative bacteria. These pathogens are also associated with meningitis in people with an impaired immune system. An infection in the head and neck area, such as otitis media or mastoiditis, can lead to meningitis in a small proportion of people. Recipients of cochlear implants for hearing loss are more at risk for pneumococcal meningitis.Tuberculous meningitis, which is meningitis caused by Mycobacterium tuberculosis, is more common in people from countries in which tuberculosis is endemic, but is also encountered in persons with immune problems, such as AIDS.Recurrent bacterial meningitis may be caused by persisting anatomical defects, either congenital or acquired, or by disorders of the immune system. Anatomical defects allow continuity between the external environment and the nervous system. The most common cause of recurrent meningitis is a skull fracture, particularly fractures that affect the base of the skull or extend towards the sinuses and petrous pyramids.
At US$5 per dose, the estimated cost per life saved was $3,015, $9,951 and $11,296 in low-, lower-middle-, and upper-middle-income countries, respectively.Safety and efficacy trials in Africa and Asia found that the vaccines dramatically reduced severe disease among infants in developing countries, where a majority of rotavirus-related deaths occur. A 2019 Cochrane review concluded that RV1, RV5, and Rotavac vaccines are safe and are effective at preventing diarrhea.Rotavirus vaccines are licensed in more than 100 countries, and more than 80 countries have introduced routine rotavirus vaccination. The incidence and severity of rotavirus infections has declined significantly in countries that have acted on the recommendation to introduce the rotavirus vaccine. In Mexico, which in 2006 was among the first countries in the world to introduce rotavirus vaccine, the diarrheal disease death rates from rotavirus dropped by more than 65% among children age two and under during the 2009 rotavirus season. In Nicaragua, which in 2006 became the first developing country to introduce the rotavirus vaccine, investigators recorded a substantial impact, with rotavirus vaccine preventing 60% of cases against severe rotavirus and cutting emergency room visits in half. In the United States, vaccination has reduced rotavirus-related hospitalizations by as much as 86% since 2006. In April 2016, the World Health Organization released statistics for the period of 2000–2013, which showed developing countries that have introduced rotavirus vaccines experienced significant decreases in deaths and hospitalizations from rotavirus diarrhea after introduction.Additionally, the vaccines may also prevent illness in non-vaccinated children by limiting exposure through the number of circulating infections.