Villena R, Valenzuela MT, Bastías M, Santolaya ME. Invasive meningococcal disease in Chile seven years after ACWY conjugate vaccine introduction.
Vaccine 2022;
40:666-672. [PMID:
34996641 DOI:
10.1016/j.vaccine.2021.11.075]
[Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 10/13/2021] [Accepted: 11/24/2021] [Indexed: 11/18/2022]
Abstract
BACKGROUND
A serogroup W (MenW) outbreak in Chile prompted a meningococcal vaccination campaign using tetravalent meningococcal-conjugate vaccines (MCV-ACWY) in children since 2012, followed by its introduction into the National Immunization Program (NIP) in toddlers from 2014. Direct protection was observed, but no indirect effects in other age-groups were evidenced. The aim of this study was to describe invasive meningococcal disease (IMD) cases in Chile between 2009 and 2019, and its trend after the introduction of MCV-ACWYs.
METHODS
IMD cases, cumulative incidence per 100,000 inhabitants, CFR, and vaccination uptake were described. Data were obtained from the Public Health Institute and NIP.
RESULTS
Overall-IMD cases increased in 2009-2014 period, followed by a decline in 2015-2019, focused in infants, children <5 years and people ≥60 years. Serogroup B (MenB) and MenW alternate its predominance. Median overall incidence was 0.6/100,000, increasing from 0.6/100,000 in 2009 to 0.8/100,000 in 2014, later decreasing to 0.4/100,000 in 2019. Median incidences for MenB, serogroup C (MenC) and Y (MenY) were 0.25/100,000, <0.01/100,000 and <0.01/100,000, respectively. Median MenW incidence was 0.53/100,000, increasing from 0.01/100,000 in 2009 to 0.56/100,000 in 2014, followed by a constant decline to 0.12 in 2019. Infants, children <5 years and adults ≥60 years were affected the most, with median incidences of 9.7, 0.9 and 0.93, decreasing to 1.3, 0.1 and 0.1/100,000 in 2019, respectively. Median overall-CFR was 19%, 7.5% for MenB and 24.5% for MenW. Median MCV-ACWY uptake was 93% CONCLUSION: Overall-IMD, MenW cases and incidence declined since 2015 after the MCV-ACWY introduction, while MenB, MenC and MenY have been stable. MenW incidence declined in all age groups, including non-immunized infants and people >60 years. Further analysis and a longer period of observation are needed to have a more robust conclusion about this epidemiological trend. By 2019, CFR remains high.
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