Epidemiology of invasive meningococcal disease and its sequelae: a population-based study in Italian primary care, 2000-2019

Background Invasive meningococcal disease (IMD) is a severe infectious disease. Although effective preventive and therapeutical strategies are available, the fatality rate remains high in the general population, with an occurrence of meningococcal-related severe sequelae involving 10-20% of survivors. Given the crucial role of general practitioners in recognizing and preventing IMD and its related sequelae, we aim to assess the burden of these conditions in primary care. Methods Using an Italian primary care database, the incidence rate of IMD was calculated in the period 2000-2019 by capturing the first diagnosis registered during follow-up. As far as meningococcal-related sequelae are concerned, we identified and clinically evaluated each potential sequela during the first 3 months, from 3 to 12 months, and up to 36 months. Results Among 508 patients diagnosed with IMD, 403 (incidence rate: 0.24 per 10,000 person-years) comprised those diagnosed with IMD in patients aged 15 years or older. We ascertained 104 sequelae (20.4%); 76% of them occurred in those aged 25 or older; 42, 27, and 35 were assessed as short-, medium-, or long-term sequelae, respectively. Overall, 4.7% of IMD patients reported physical sequelae, while 12.2% and 5.7% of patients reported neurological and psychological sequelae, respectively. Conclusion Our study showed that a substantial proportion of IMD and related sequelae occur in individuals aged over 25, with a non-negligible burden for healthcare systems. As for the paediatric population, effective communication on the relevance of meningococcal vaccination in adults should be proficiently fostered.