Meningitis is a serious condition that can result in death, but is entirely preventable through early vaccination in childhood. Western Australia has demonstrated a great public health achievement by reducing its yearly meningitis cases through vaccinating most school-age children.
The causative agent, Neisseria meningitidis, can be divided into serogroups A, B, C, W and Y, which are commonly associated with invasive meningococcal disease (IMD). IMD has a rapid clinical manifestation. Its sudden onset of symptoms includes fever, stiff neck, nausea and a spotty red-purple rash, eventually progressing to septicemia or meningitis. Those younger than one year are most at risk of infection, partly due to a lack of hygiene practices and a higher tendency to touch objects in their surrounding and then their mouths, thus increasing their chances of coming into contact with N meningitidis. A second, but much smaller, peak in incidence is found in adolescents and young adults, reflecting social behaviour that facilitates faster transmission of nasopharyngeal N meningitidis.
The best method of prevention is through vaccination against the common meningitis-causing N meningitidis serotypes. The seriousness of the condition presents a significant public health problem, but it can be effectively lessened through the continuation of vaccine immunisation programmes until nationwide coverage in Australia is achieved.
The effectiveness of vaccines against meningitis was demonstrated in Western Australia. In 2016, the government of Australia began the incremental rollout of a meningococcal N meningitidis serotypes A, C, W and Y (MenACWY) vaccine.
The area subsequently saw decreases in meningitis cases, reaching its lowest rate in 2020, which was the last recorded year to date. With vaccine implementation occurring at the current rate, GlobalData epidemiologists estimate that there will be 294 confirmed incident cases of IMD (all serotypes) in Australia by the end of 2024 in all age groups of men and women. That number is expected to rise to 304 confirmed incident cases by the end of 2029. However, it is worth noting that this slight increase in cases is mostly attributable to changes in the Australian population.
The MenACWY rollout in 2016 in Western Australia began with vaccinating relevant schools, community health centres and immunisation clinics. Almost a year following its initial rollout, the vaccine was offered to children (aged 12 months to four years) and teenagers (aged 15 to 19 years) still attending school in at–risk communities and regional areas. Eventually, full coverage was reached for children aged from 12 months to four years, as well as for those not attending school who were aged 10 to 12 years and 15 to 19 years.
New cases of IMD were captured in the surveillance database managed by Communicable Disease Control Directorate at the Western Australia Department of Health. IMD notifications between 2012 and 2020 were analysed to quantify the impact of the vaccine rollout on meningitis incidence in Western Australia.
A board overview of the surveillance database shows that a total of 216 IMD cases were reported between 2012 and 2020. Of those cases, 98.6% were laboratory-confirmed cases and the remainder were diagnosed based on high clinical suspicion of meningitis. Of the 216 IMD cases, 61% occurred in residents of the Perth Metropolitan area, which is home to approximately 80% of the Western Australian population.
During the nine years, the IMD age-standardised notification rate fluctuated from 0.8 per 100,000 population in 2012 to 1.8 per 100,000 in 2017, dropping to 1.6 per 100,000 in 2018 and then dropping again to 0.9 per 100,000 in 2019, before declining to the lowest rate of 0.4 per 100,000 in 2020. During the partial rollout of the vaccination programme, Western Australia experienced a breakout of N meningitidis serogroup W (MenW), explaining the rise of the notification rate in 2017. In recent years, the IMD notification rate has decreased as vaccination coverage in Western Australia has expanded.
The MenW outbreak was mainly concentrated among Aboriginal populations between 2017 and 2019. During this period, 65% of IMD cases among Aboriginals occurred, and 65% of those cases were in children younger than five. This resulted in an overall IMD notification rate of 4.9 per 100,000 population in the Aboriginal population - seven times higher than the non-Aboriginal population, which had an overall IMD notification rate of 0.7 per 100,000 population.
The effectiveness of the vaccine in preventing cases of meningitis was calculated for the 12 months to four years age group, where it was 93.6% for 2018 and 92.5% for 2019, thus showing that the vaccine provides an excellent level of protection. This surveillance database has shown that comprehensive vaccine coverage for IMD aids in reducing disease incidence. It also highlighted the demographics that were more at risk of infection, such as the Aboriginal population, and where the allocation of resources for prevention can go to help prevent endemics in those high-risk communities.
