The epidemiology of invasive meningococcal disease and the utility of vaccination in Malta

Abstract

Invasive meningococcal disease (IMD) is a vaccine-preventable devastating infection that mainly affects infants, children and adolescents. We describe the population epidemiology of IMD in Malta in order to assess the potential utility of a meningococcal vaccination programme. All cases of microbiologically confirmed IMD in the Maltese population from 2000 to 2017 were analysed to quantify the overall and capsular-specific disease burden. Mean overall crude and age-specific meningococcal incidence rates were calculated to identify the target age groups that would benefit from vaccination. Over the 18-year study period, 111 out of the 245 eligible notified cases were confirmed microbiologically of which 70.3% had septicaemia, 21.6% had meningitis, and 6.3% had both. The mean overall crude incidence rate was 1.49/100,000 population with an overall case fatality rate of 12.6%. Meningococcal capsular groups (Men) B followed by C were the most prevalent with W and Y appearing over the last 6 years. Infants had the highest meningococcal incidence rate of 18.9/100,000 followed by 6.1/100,000 in 1-5 year olds and 3.6/100,000 in 11-15 year old adolescents. The introduction of MenACWY and MenB vaccines on the national immunization schedule in Malta would be expected to reduce the disease burden of meningococcal disease in children and adolescents in Malta.

Keywords: Conjugate vaccination; Epidemiology; Malta; MenB vaccination; Meningococcus.

Fig. 1

Flow diagram of analysed cases

Fig. 2

Number of IMD cases per year

Fig. 3

Mean age-specific incidence rate of IMD in Malta from 2000 to 2017. Error bars represent 95% Confidence Intervals

Fig. 4

Crude incidence rate of MenB, C, W and Y disease (2000–2017)

Fig. 5

Distribution of meningococcal capsular groups by age (2000–2017)